This is a reverse die trial, in copper, from the 1836 Gobrecht dollar reverse with stars. It shows partial die breaks through some of the letters in "Nited States O" and has the raised die mark under the crossbar of the "A" in "States" and was likely made in the 1870s. Much of the die crack is incomplete probably due to the stretching of the design at the periphery.
It has a long pedigree including Steigerwalt 12/1884 lot 1989, Steigerwalt 4/1885 lot 990, Woodside, Woodin-1914 ANS, Lohr, Batchelder (see Numismatist 2/62), Empire Review 1/63 FPL, R.B. White, Bowers and Merena 9/89, Share, Dr. Korein, ANS.
Photo courtesy of Heritage.