I am not real sure but, it could be a vehicle registration tag. Most of the ones I have seen are a little different than the one you have pictured. They tend to be aluminum, round, and about 2" to 2.5" in diameter. They also have the engraver's name on the reverse side. This does not really fit what you have pictured but, the info., on the obverse side is close to what is enscribed on the ones I have seen. Hopefully, someone out there in treasure land can be more specific as to what it is.
In any event, it is a great find and I wish you the best.
BondJamesBond.