A childhood rhyme goes a little something like this: “Find a penny, pick it up, all day long you’ll have good luck!” But what if you found a penny, picked it up, and it was worth millions of dollars?

Add Yahoo as a preferred source to see more of our stories on Google. Penny production in the U.S. is grinding to a stop. More than 3 billion pennies were minted in the U.S. last year, but according ...