Presidential Dollar Program
From the U.S. Mint website:The United States is honoring our Nation's Presidents by issuing $1 coins featuring their images in the order that they served in office. The United States Mint issues four Presidential $1 Coins each year, with Presidents Arthur, Cleveland (first term), Harrison, and Cleveland (second term) being honored in 2012.
Each Presidential $1 Coin has a common reverse design featuring a striking rendition of the Statue of Liberty. These coins feature large, dramatic artwork, as well as edge-incused inscriptions of the year of minting, or issuance, E PLURIBUS UNUM and the mint mark.