2008 United State Mint Presidential Dollar Proof Set. 4 Coins Inside. No Outer Box. United State Mint Presidential Dollar Proof Set 2008 4 coins, the set includes proof versions of the general circulating $1 Presidential Dollars. 2008 Set include Benjamin Harrison, John Tyler, James Polk and Zachary Taylor. The Presidential $1 Coin Program, launched in 2007, pays tribute to the Presidents of the United States in the order in which they served. These proof coins are struck multiple times with specially polished dies to create a brilliant, sharp relief and mirror–like background. Their frosted, sculpted foregrounds give them a special “cameo” effect. Each coin bears the “S” mint mark representing production at the United States Mint at San Francisco.