This is the infamous 1792 eagle on a half shield - also known as rock - design struck by Montroville Dickeson in the early 1860s from rejected embossing dies for stamping revenue paper.
It is thought that Dickeson believed that these dies were rejected designs for 1792 cents, had a reverse created, and struck these coins in the early 1860s.
The reverse die was offered in an Empire Coin Company 3/59 mail bid sale and was stolen shortly after the sale. Prior to this, the die sold as lot 59 in Elder's 5/17 sale.
Examples are known in both copper JC1792-1/P6001 with about a dozen known and white metal JC1792-2/P6005 with only 2 or 3 known.
Photo courtesy of Heritage.