Did you get any early military buttons? A true Loyalist site seems to almost always give up a Rev War military button, and usually more than one.
To answer your question it's definitely a nice early silver shoe buckle and would date to the right era. I found pieces of one several years ago that would have been stunning, makers marks and all, just too bad it was destroyed. Ironically, the bits I found was from the site of a Loyalist officer, but not just any one, this particular site gave up a button that was the first of the type known to exist. It wasn't my find, unless getting it in my email inbox for ID counts!