Dapman, tend to agree with Ronstar for a couple of reasons.
First, the light construction of the loop fastenings. Not that they don't exist, but could not find any military examples matching that style of the back with the crimped over flanges fastening the D-loops. This puts me in mind of the minimal design of the pressed metal products coming out of Japan during the 50's and 60's... designed and manufactured for minimal cost to produce. As well, attracted to a magnet.... looks like a bronze or brass copper alloy which are not generally magnetic, however, particularly in foreign production, iron dust was often added to the alloy which will make it somewhat magnet. Again to reduce the cost of production.
As well, the image of the eagle is very primitive, even amateurish, particularly with the wing and feather detail. So much so, it's hard to say what the eagle is perched on... Eagle on mountains? Partridge on a moustache?, ha... Below is the closest I could find to the design, a 2 piece militia waist plate, eagle facing dexter, wings extended pointing down, albeit with 13 stars and perched on a shield. There are similar designs to this with the eagle perched on clouds.
And we also have the 14 stars... on top of the crimped loop attachments, the magnetic properties, and the poor detail of the pressed eagle image, it's a fair guess that the dies for this plate may have been engraved by an artist who did not understand the significance of 13 stars,,, and maybe the shield on the example he was copying was half worn away and not knowing what it was supposed to be, just made something up as best he could? Again, possibly pointing to foreign manufacturing. Japan? India?
Best guess, but that said, please have it checked out by an expert. You'd hate to throw it back in the drawer and forget about it again if it happens to be a rare Green Mountain Boys militia belt plate from 1812, ha!
At the link below, a good selection of early US military belt plates with detailed descriptions. As you scroll through, notice the intricate detail in the eagles, even on the very early items.