This is not a weird question at all, and I've handled this topic several times in the past.

Here is my write-up of the transformation in bread that began in the nineteenth century. Medieval bread would have been quite similar to what I describe there as the "before" kind of bread. And here is a write-up I did of medieval flour milling.

[I've edited this series of posts substantially to make more sense]

Here are my thoughts on the methods and materials of medieval bread:

As I indicate in the excerpt from my work below, wheat began to displace other grains in the eighteenth century. Medieval bread was often made with barley, rye, or sometimes oats in addition to wheat. Also, as noted below, all flour anywhere before about 1860 was stone-ground, and most of it was until about 1880. Stone mills at the time used what was called the "low-grinding" or "sudden death" method, in which the grain was simply poured into the hopper and ground into meal in one go. The kinds of grain grown in Britain at the time were relatively soft and moist, the wheat especially (dry and hard grain that was imported in the nineteenth century was another story), and the bran tended to simply flatten out in the process. Once ground, the meal could be sifted or "bolted" to remove those relatively large, flat pieces of bran. The breakdown of flour from a stone mill was something like 25% fine flour, 50% seconds flour (which was often re-ground), and 25% offals, not considered suitable for human consumption. However, these figures were highly variable depending on the variety and quality of the grain, the skill of the miller, and the preferences of the consumer. In addition, the grain grown in Britain at this point was "weak" or "soft" in the sense that it didn't have very much gluten. I'll explain why this is important below.

In terms of yeast, as far as I can tell (I'm working on this for my current chapter), there was no "yeast" employed before probably the eighteenth century. Instead, bakers leavened by using a bit of dough left from the previous day mixed into the current day's batch. I'm not sure exactly how they did it, because the earliest detailed description I've read is 1828, but I suspect they used a pretty basic straight dough method: they mixed the flour and water up all at once, included some of yesterday's dough, and then let it rise from there. It would have been a pretty slow process, and probably wouldn't have risen all that much. At some point around the eighteenth century--it's pretty difficult to figure out when--bakers began getting access to brewers' yeast, which gave them a great deal more fermenting power, and which brought about the use of half- and quarter sponges, and more rigorous fermentation methods such as using potatoes or malt.

The possible complication to this timeline is that in the medieval period, people brewed a lot of their own beer in their homes. I don't know the process for this, and don't know if they used yeast as such or if they had some other method of fermentation. Further, such brewing would have theoretically made possible the use of materials from brewing in baking, so they may have done. However, the sources I've read say that bakers used yesterday's dough to leaven, so it's hard to know for sure without a rigorous study of the medieval baking sources, which I have not (and cannot) do.

Overall, with fairly gluten-poor grains ground on stone mills, and fairly weak leavening materials, it's pretty clear that the vast majority of bread consumed in medieval Britain was dark, dense, and pretty heavy. I happen to like bread like that, but it's much different from the high, light, sweet, and white loaves that were developed by the late nineteenth century.

To expand on all this, here is an excerpt from the most recent chapter of my dissertation. It covers much of the context of bread's production and regulation. Much of my excerpt deals with the changes that occur beginning in the eighteenth century, but they are useful for this conversation because "medieval" bread is pretty consistent up to the changes I discuss below. Plus, this will discuss the moral economy that governed bread's position in economy and society.

From my chapter "Baking and the Biopolitics of Bread":

In medieval and early modern Europe, the “problem” of bread was guaranteeing its supply. Before the modern period, grain markets across Europe were essentially local in orientation, owing to high transportation costs, a fact that meant that local shortages could not be made good from neighboring surpluses. The price of wheat and bread, essential elements of social and political stability, were closely tied to a particular locality’s harvest, and were therefore focal points of state regulation. Wheat and bread were subject to a comprehensive system of legislation that included the Corn Laws, Poor Laws, statutes against regrating, ingrossing, and forestalling, and the Assize of Bread, as well as common laws and customs, all of which operated to either strictly regulate the markets for wheat and bread, or remove those items from profit motives altogether. This regulation occurred alongside what E. P. Thompson has described as a “moral economy” of wheat, flour, and bread: a “popular consensus” prioritizing as direct as possible a relationship between producers and consumers, with few or no “middlemen” between those who farmed grain and those who ate bread. Indeed, Thompson argues that middlemen remained “legally suspect” through the eighteenth century, with their activities severely restricted, at least in theory. For the bulk of the population through the medieval and early modern period, home baking was the rule. To supply them, farmers were obliged to sell to individual consumers first, in small amounts, at regulated prices and weights, and in controlled spaces; only after the general public had an opportunity to secure their supplies were farmers permitted to sell to licensed dealers. To prevent speculation, hording, or other manipulation of supply and demand, sales could never be made by sample or of corn still in the field. For the home-baking population until the eighteenth century, the only intermediary between farmer and consumer was the local miller, a tradesman who operated not for profit, but for a customary toll. In many locations, mills were covered by the right of “soke,” an obligation of local residents to have their corn ground at the mill constructed at the local lord’s expense.

In cities and towns, London especially, home baking gave way to commercial baking much earlier than in the countryside, and in those situations, the baking trade was regulated by the Assize of Bread. The inelasticity of bread’s demand and the lack of alternatives meant that bakers might abuse their position, colluding to raise prices; at the same time, should baking not be a viable trade, bakers might close their ovens. Both cases jeopardized the food supply and social stability of the town. First enacted in the thirteenth century, the Assize of Bread tied the price of bread to the price of wheat: magistrates set the size and price of loaves, varying one or the other as the price of wheat changed, with a fixed “allowance” included to cover the bakers’ costs and provide a modest wage. Connecting the price of wheat and bread also necessarily included mandating standard qualities of bread, an exercise which recognized dozens of varieties, from “Wastel,” a fine, white bread with the highest price, to “Cocket,” “French,” “Ranger,” and “Bread Treet,” each with specifications as to quality, ingredients, methods, and price. Over time, these categories were simplified, reduced to “White,” “Wheaten” or “Household,” with specific relationships between them in both weight and price. Between the non-commercial nature of millers and the Assize of Bread, both millers and bakers in medieval and early modern Britain were essentially public servants, operating not for profit but to provide vital services for customary fees. It was in this manner that they fit into the moral economy of bread: C. R. Fay argued that, “in a matter so vital as the delivery of food, no autonomy, no rights against society were suffered.” Aside from prices, bakers were largely self-governing, with minimal state intervention. Corporate bodies representing bakers existed in larger towns throughout Britain; the Worshipful Company of Bakers of London, the largest, was incorporated certainly by the thirteenth century, and perhaps as early as the twelfth. The Company was responsible for regulating retailing, labor, and quality through an internal court empowered to punish bakers publicly and financially, a system that seems to have worked to the satisfaction of both the bakers and the City of London. Through at least the seventeenth century, the Company enforced its regulations effectively enough that the City made almost no attempts to intervene in the trade, aside from setting the Assize.

I'm not a historian, but I've been reading a book called "Food and Feast in Tudor England" by Alison Sim lately. It discusses the importance of bread to Tudor diets at least, and I'll transcribe the part that discusses ingredients below:

"At all levels of society, bread was eaten, though the main ingredient would differ. Wheat was considered the finest flour for bread making, but bread was often made from other grains, such as barley, or from a mixture of grains, known as maslin. The poorest bread, made of ground-up beans, was known as horse bread as its usual use was to feed horses. Those at the bottom of the social ladder might also find themselves eating it."

Oh, and I didn't think to include the relevant parts about method as well as ingredients. Silly me! The book later goes on to discuss the contents of various qualities of Tudor kitchen, and of bread making equipment, it has this to say:

"As bread was very much part of the staple diet at the time, some sort of oven was needed. They were usually built into the wall, often next to the fireplace, and a fire would be lit inside. Once the oven was hot enough the fire would be raked out and then the bread, or whatever was to be cooked, would be put inside.

It was very expensive to heat an oven and so there were other, cheaper ways of baking bread. In areas where oatcakes, rather than leavened bread, tended to be eaten a bakestone was often used. This was usually made of metal rather than stone and took the form of a round plate which rested on four legs. This could be stood over the fire and the oatcakes cooked on top. The bakestone could also be used to bake unleavened bread. In this case, the bread would be put under an upturned iron pot. The bakestone would be placed over it and hot coals would be built up over the pot and bakestone to make a kind of oven."

One thing we take for granted nowadays is Yeast. In the medieval world nobody knew what yeast was or why bread rose/alcohol fermented, just that it worked. This meant that all bread and beer was made with Wild Fermentation, i.e. using whatever strain happened to be indiginous to your area, meaning the same recipe in London and Berlin could produce two (slightly) different tasting breads, with different levels of "puffiness" and acidity. Also (not that you asked this) but bread wasn't formalized until relatively recently considering it goes back to beyond antiquity. Napoleon set standards in France for how bread was to be made and with what quality ingredients- France had just had a bread shortage and people were making bread with sawdust and chalk as filler, this became illegal. Before Napoleon it wasn't uncommon for a loaf of what we know call french bread to be circular.

It seems to have not been mentioned below but you may also be interested to know that the wheat of today (engineered in the 1960s) is so completely different from the wheat of bygone days you wouldn't even recognise it growing in a field.