I used to donate breast milk. No medal, but we do get a nice Christmas card with a Milk Bank update, and a Milk Bank calendar (think the printing must be done as a charitable donation because our local bank is very efficiently run, they wouldn't spend unnecessarily).
And when I first started I got an insulated cool bag and free bottle of hand soap (again , think this was some kind of sponsorship or promotion).
So as you can see, the rewards are plentiful and extravagant. Plus, it's really not that much extra hassle to do an extra bottle if you are expressing anyway.