If You Have a $20 Bill With This Mark — You Might Be Holding Something Rare

in the background details — is believed to come from a rare printing plate flaw or ink bleed that occurred during certain production runs. Because the U.S. Treasury prints millions of bills at lightning speed, a handful of them escape with unique imperfections that turn into collector’s items later on.

If you ever find a $20 with strange symbols, doubled continue reading …