American Silver Eagles Certified. The American Silver Eagle program was signed into law by President Ronald Reagan on July 9, 1985 as the "Liberty Coin Act". On October 29, 1986m first Silver American Eagle was struck at the San Francisco Mint. The coin is struck in only one ounce size and is guaranteed to be on troy ounce of pure 99.9% silver. The Silver American Eagle is struck in both uncirculated and proof issues and bears the $1 denomination.