On March 8, 2007, the US Mint announced that on February 15, 2007 an unknown number of George Washington presidential $ 1 coins were released into circulation without their edge inscriptions ( the US Motto's, "In God We Trust" and E Pluribus Unun"( the coins mint mark, and it's year of issuance.
Estimates of about 50,000 coins got released without their inscriptions.
Also, John Adams 2nd Presidential Dollars have been discovered with plain edges. There were fewer coins of PLAIN edges making them RARER. Other problems arose in the minting of the Adams Coins but NO edge marks made them more popular.