The pennies used today have been around since 1856 when they were first minted. At that time, though, they were referred to as "Small Cents," because they replaced the larger-in-size Half-Cent and Large Cent.
The United States began issuing Small Cents in 1857 for two reasons: first, the cost of making the larger size Half-Cent and Large Cent had risen to the point where making the coins cost more than they were worth. Second, Small Cents were meant to encourage citizens to move away from using Spanish and English coinage and begin using U.S.-issued decimal coinage.
Although today's pennies are technically Small Cents, someone who refers to Small Cents likely means coins that were issued when the coins were first introduced.
However, Small Cents, even if they're relatively old, aren't particularly valuable. While earlier coins were made of gold and silver, Small Cents are made of a combination of copper and nickel. In addition, most were made in large quantities, so they're not rare coins.
They are, however, a lot of fun to collect and display. Most can be found at flea markets, coin shops, and at auction. Keep your eyes open, however, for rarer variations; some Small Cents were produced in very low quantities, and others—such as the over-polished 1922-D without Mint mark issue—were produced in error. Keep in mind that all values are estimated and conditional, meaning the penny would have to be in good shape to earn top dollar.
- Flying Eagle Cent: The first Small Cent, the Flying Eagle Cent, was issued as a pattern type in very small numbers in 1856, and business strike coins began in 1857. The Flying Eagle Cent didn't last long, though, with 1858 being its final year of issue. Specimens in the G-4 grade of the 1857 and 1858 coins are worth about $15 today.
- Indian Head Cent: The so-called Indian Head Penny, which is actually a depiction of Lady Liberty wearing a feathered headdress, is a very popular type today. It replaced the Flying Eagle Cent in 1859 and was issued until 1909. An Indian Head Cent in G-4 condition will bring at least a dollar if you want to sell it, but rarer dates could bring more.
- Wheat Ears Cent: The Wheat Ears Penny, also known as a feather back or wheat back penny replaced the Indian Head pennies in 1909 and were made until 1958. Wheat pennies range from 2 cents to 20 cents in value, depending on the date. Some rarer coins are worth more; the very low mintage 1914-D and 1931-S, for example, may be more valuable.
- Lincoln Memorial Cent: The next issue of U.S. Small Cents is the Lincoln Memorial Cent, which began circulation in 1959 and was made until 2008. All Lincoln Memorial Cents prior to 1982 are worth at least 3 cents (for the copper bullion in them), and business strike cents after 1982 must be in fairly high grade (MS-60 or better) or a variety type to be worth more than face value. For pennies dated 1982, you need to determine whether they are primarily copper or zinc in order to ascertain their value.
- Lincoln Bicentennial Reverse: In 2009, the United States Mint issued four different reverse designs for the Lincoln penny. This was done in order to commemorate the 200th anniversary of the birth of President Abraham Lincoln.
- Lincoln Shield Reverse: Beginning in 2010 Lincoln pennies had a new reverse that featured a shield in order to symbolize the work President Lincoln did in order to maintain the unity of the United States.