As Cru already mentioned, it's more likely to be a clothing 'snap' or a rivet.
I'm not entirely sure that's a 'Dragon', it may just be the corrosion playing tricks on our eyes.
Throwing this out there as a possibility, as I’m not sure, and wonder what others’ opinions might be:
It looks like it might be a Jacksonian waistcoat button (1830’s mostly) which is missing it’s applied outer rim. And then on the back is there maybe a piece of crusty old material (leather perhaps?) which is making it hard to see the loop correctly?
I do see it as a griffon, as suggested.