Sorry, I don't look in this part of the forum very often, so delayed response. Your picture is upside down, but it says "chai ben" which is sort of like "know how to use [it]" or "able to use." Thai generally leaves out pronouns, so the meaning is only clear with context...which you don't have. My best guess is it could be a gambling token, but that's just a guess. It is not a coin.