Pennies made prior to 1982 have a copper content that is worth more than their face value. Wheat pennies issued between 1909 and 1956 are also worth more to collectors than their face value.
Pennies minted before 1982 are made of 95 percent copper (about 2.95 grams). As of 2014, copper prices have risen such that this amount is worth a little more than two cents when melted down. However, destroying currency is a crime, so it is difficult to redeem this value. Indian Head pennies (minted from 1859 to 1909) and wheat pennies typically have a value to collectors that is greater than the currency face value.