So, no, I technically don't know of any codpieces that were considered important in their own time. The codpiece was a vital accessory, used to cover the opening between the left and right hose once the doublet shortened enough for that opening to come into view during the fifteenth and sixteenth centuries - but it wasn't a particularly valuable one. Codpieces were made out of the same fabric as the hose, whether the full hose of the fifteenth century (where it was a flap to cover the opening) or the fuller, short trunk hose of the sixteenth. See, for instance, this portrait of a boy with a greyhound by Paolo Veronese, from about 1575: the codpiece is recognizably part of a set with the trunk hose, decorated in accordance with them. It simply wouldn't make sense to take a codpiece out of a set and pass it to someone else - it wasn't worth that much money, and it didn't really have sentimental value, either.

There is a codpiece that's particularly memorable in another sense, however: the one in the famous full-length Holbein portrait of Henry VIII. As you can see, the codpiece is a part of the suit as a whole, made of the same silver damask as the doublet and trimmed with the same white silk puffing out between the silver strapwork. It's memorable because this portrait is probably the most famous image of a person in a codpiece, and because it's the focal point of a lot of art history discourse on this painting. The king's stance makes his body an X, with the codpiece at or near the center point, drawing the eye to it; Henry was, of course, obsessed with being seen as a virile and healthy man capable of producing sons, and the bulging codpiece suggested his genitalia. More metaphorically, the suggested large phallus could also represent other facets of his masculinity - political skill, martial dominance, etc. But this codpiece was almost definitely not passed down to anyone unless it was transmitted with the rest of the suit as a gift to a favored courtier or a servant who was entitled to handed-down clothing as a perquisite, a tradition that Henry and his wives and children participated in.