“Find a penny, pick it up.  All day long you’ll have good luck!”

Not all good luck charms have their own little rhyme, so I suppose the penny is extra lucky.  That, and my sister loves Abraham Lincoln.  From what I have read on the subject, the luck of picking up coins comes long before the penny’s existence.  In ancient times when coins were used as currency, finding loose change on the ground was considered a gift from the gods!  The extra layer of superstition with the penny depends on whether the coin is found heads up or heads down.  Apparently, you can also turn a heads down penny over, to let the next finder collect the luck – it is only considered bad luck if you take it with you.  You know, if you believe that sort of stuff.