As everyone would know (well, most people), a penny is the least valuable form of US currency.
Typically, collectors go for unique items or those with extremely rare characteristics.
Most of these are antiques with some dating back to centuries and a few, millenniums ago.
As for the case of coins, collectors are looking for pennies which were printed at specific times, or have unusual characteristics with other similar coins.
In 2004, the Wisconsin state minted a quarter that had an extra leaf on the husk of the corn.
Out of the thousands that were manufactured, only a few of these were released to the public, and the remaining were withheld when the mint discovered the mistake. It was rumored that a worker had done it on purpose.
Whether it was a mistake or not, the penny is now valued at about $1500 with a perfect chance that a zero may be added at the end if it is at an excellent condition.
All coins made in the States are marked to show where they were minted.
Those with a P were minted in Philadelphia, D in Denver and S in San Francisco.
In 1982, however, the mint at Philadelphia somehow forgot to sign their Roosevelt dime.
This mistake is now earning people a good amount of money with others selling it for as much as $300.
With these and many more being bought at remarkable prices, you might want to find your coin box and look through the assortment of pennies that will earn you a quick buck.
Be sure, however, that your lucky penny is authentic or you might face a series of unpleasant lawsuits.