This is a Eisenhower dollar blank, with no raised rim.
The blank has proof-like surfaces, with the surfaces having an unusual deep, slightly mirrored appearance. There are many tumbling marks on the planchet as you would see on a proof planchet. Is it a proof? Possibly, or it could simply be some sort of test piece. The blank is ex-San Francisco Hoard, which had many test and experimental blanks and planchets in it. This is certainly not a normal business strike blank, and there is no question if was specially prepared for some purpose. Neat blank, and a good one to study.
NGC certified but not graded since they do not grade planchets or blanks. It is problem free and mint state.