I had received a twenty dollar bill once that was from the 1930's. It was somewhat beat up and wasn't really worth anything to a collector (I checked). I just kept it in my wallet.
One night though, I was really hungry but didn't have any other cash on me or an ATM card. I decided "Oh, what the hell. I'll just use the old 20". Wrong. I went to 3 different places and they wouldn't take it. They just assumed it was fake because it looked different from what they were used to.
I finally ended up spending it in Vegas, years later. They took it in a heartbeat.
