Take a look at the Harvey's Lake Tahoe $1 tokens from 1964 (see ChipGuide). Especially the Franklin Mint one.

I sort of recall a written article (or maybe just a conversation) with Howdy Herz about the time when $1 cartwheels were becoming scarce. And Harvey's (among other casinos) hired Franklin Mint to produce tokens, as FM was already in the commemorative medal/token business. I think the U.S. Mint had to give permission for casino tokens to be made, as it was previously unlawful for such items to exist for monetary exchange.

Maybe check the back issues of club magazine, or directly with Howdy.

Hope that's a start.