it looks to me to a butiful exsample of a "scute" from some sort of reptile. most likely croc or aligator. these are the bony lumps and bumps that you get on the back of crocs it acts a a sort of bony protection.
how heavy is it?
if it is light for its size it is more likely to be from a reptile that is not a fossil an will only be very young. but if its heavy it may be a fossil exsample.