An auction site called U.S. Currency Auctions estimates that uncirculated $2 bills from 1890 could sell for at least $4,500.

You probably won’t get lucky enough to have one that old lying in the back of a drawer or up in a box in your attic. So what about more recent ones? You never know until you check. A $2 bill issued in ...

If you do find old currency or something that could potentially be valuable, one word of advice: Don’t clean it. “Cleaned coins lose a significant value in the marketplace. Collectors prefer ...