This is an interesting question. In contrast to modern coinage which is largely symbolic, Medieval English currency was valued very much by its weight. English coinage, particularly in the Early Medieval Period, was renowned for its consistency and quality. By the 14th Century, when Knight's Tale is set, the predominant coinage was the "Long Cross" penny of Edward III, which was a vast refinement on earlier pennies, following a sweeping series of reforms carried out by Edward I. A number of popular new coins also entered production, including the 4d 'groat', 2d 'half-groat' or tuppence, and the new golden 'noble' worth 80d, which was the first golden coinage to see relatively widespread circulation.

Unfortunately for our heroes, Roland says that their 15 silver coins are 'florins'. This might be a simple accident on the part of the scriptwriters, as there was a 19th Century British coin called a florin which was worth 24d (2 shillings, one tenth of a pound). In the 14th Century, however, a 'florin' referred to an Edward III penny struck between 1344 and 1351, so called because the die-makers were from Florence. If our heroes had indeed been given the Victorian florin, then they would have ended up with the princely sum of some 360d, or 1 pound 10 shillings, but unfortunately using the Edwardian florin their 15 coins are just that: 15d.

Working out the value of the trophy is a bit more complicated. If memory serves, then the trophy from the first tournament is a golden peacock feather; presumably one that's been gilded rather than cast from solid gold. This is itself a problem, as we have to wonder at the historicity of this as an item. Let's assume, however, that rather than a feather sprayed gold by the props deparment, our feather has been painted using the contemporary techique of applying 'shell gold' mixed with gum arabic or ground gold leaf powder mixed with gesso as a kind of gold paint. I couldn't begin to estimate how much gold you'd need to gild a peacock's tail feather, but according to Dr. Graham Askew of the University of Leeds School of Biomedical Sciences, they can be 1.5m long and weigh up to 300g each. The movie feather is considerably smaller than the 1.5m that some peacock feathers can reach. If any of my fellow historians happens to be able to provide a more accurate estimate of the weight of gold required to gild a ~50cm peacock feather, please do let me know. Gold leaf is extremely thin and lightweight, so it's unlikely to be more than a few grams. If the feather was solid gold, we'd be in for a different story: At the time of the movie, 1356, a gold 'noble' weighed 7.8g, so a 100g golden feather would be worth just shy of 13 nobles at 1025d, or 4 pounds 5 shillings and 5d. Our gilded feather, on the other hand, contains far less gold. A 5mm diameter nugget of gold (1.25g) can reportedly produce 0.5m^2 of gold leaf, so let's go with that and say that there's about 2g of gold used, which is worth about 10d.

Even using Edwardian florins then, Roland got a good deal.