I'm pretty sure it's Thailand but I don't have any specifics. Edit: If you look at Fuang coins from the 19th century Thailand I think you'll find a match.
It's either a 1/8 or 1/16 fuang of the 1862 series, it's too corroded to see the denomination from the pictures. Tin coins like these didn't hold up very well in the hot, humid climate of Thailand.