The button on the left looks like flat button from the second half of the 18th century, probably more likely the last quarter of the 18th century until around 1800 or so. Is it slightly curved? If not it looks like it might be spun back from the second photo, though that is most common on white tombac buttons. The other button looks like an 1890's era overall button most likely. Awesome finds, love the buttons and beautiful green color on that IH!