American pennies have always contained copper--with one notable exception. In 1943, a shortage of copper that was needed for the war effort prompted the U.S. Mint to make pennies from steel. They were coated with zinc to prevent rust, which gave them a silvery gray appearance. Even though they are a novelty, enough of the coins were minted in that one year that they do not hold any special value.
Grade the condition of the coin. The four main grades of coins are Good (G), Fine (F), Extra Fine (XF) and Uncirculated (U). Uncirculated coins look much like they did when they left the mint, except for a slight tarnish from age. If the coin does not meet this standard but all the details on both sides of the coin are sharp and crisp, it is in XF condition. For the lower classifications, grade the coin by examining the wheat stalks on the reverse side. If the lines along the length of the stalks are all clearly defined, the coin is in Fine condition. Good condition requires that all the general design features of the coin are visible and the date and mint mark are legible.
Verify the date on the coin. It is stamped on the obverse (front) side near the bottom, just in front of Lincoln's chest. If the date is not legible due to wear or damage, your work is done; the value of the coin is one cent.
Find the mint mark that is stamped just below the date. If you see an "S," the coin was minted in San Francisco. A "D" indicates the Denver mint, and the absence of a mint mark means the coin came from the main mint in Philadelphia.
Establish the value of the coin by looking it the grade and mint mark online or in a reference book (see Resources).