Anybody Know What This Is?

[motor-officer]

I came across some of these and hope someone can tell me what they are. They were bundled in groups of four.
The edges are sharp so I believe they were stamped out. It appears they have been case-hardened.
The approx. dimensions are: 2 11/16" wide, 1 1/2" across the circular section, and between 1/16" & 1/8" thick.
Thanks for any help.