I believe this is the center of an old Caesars Palace $100 token. It's marked 10K gold and is about 1 3/16" in diameter. The edges are not reeded but are somewhat irregular, making me think someone pressed it out of a complete token.

I have a number of other 20th anniversary tokens from Caesars dated 1986 but have never run across the $100. I'd like to buy or trade for the complete token if someone has an extra.