Your token is listed in the reference on Nevada Casino Promo Tokens. There are two that appear to have the same image as yours. Cat. 423.0 is 52 mm in diameter. Cat. 898.0 is 51 mm in diameter. Both are metalized plastic. Stated value is $8-15.

The book doesn't say so, but sometimes these light aluminum or plastic tokens are really Mardi Gras token, thrown from the floats in the annual spring parades in New Orleans.