I remember seeing those coins in a small satin lined, slender box. I believe they were four coins in the series and issued by the Grand Casino, Gulfport, MS. They were given as a premium for loyal customers who contributed at the table games. The one you showed is the Mississippi Brown Shrimp, commonly referred to as "Brownies." They get their name from their coloration but are the first shrimp caught making their way into the Gulf Of Mexico after a successful spawn in the inlet bays and marshes.
Probably more than you wanted to know, but that's the best I can do for now!