OK, not the best example, but the horse buckle ID doesn't change from circa mid-19th.actually several pre-1800s finds were made. Many lead/pewter spoon pieces, some dandy buttons, one with etched flower design (seen in shot) and if you look at the group shot right under my plate is a lead or pewter cast spanish reale button or cuff link. (very dirty in pic but you can clearly make out the pillars)
This is my reference for American Military plates. Sorry the pictures uploaded from my phone came up sideways
With the largest signals such as that buckle, there may have been people that "passed" on it, assuming it's junk. I've found several 1820's and CW plates and they all sounded like cans. Lol
Here is another one from the same book which is the third edition 2010. Note that the dimensions are slightly different from the last one I posted.I would like to point out that neither of these designs match my plate. Refer closely to my eagles neck and you will see they are not the same.