My oldest silver coin - I think?

Hey everyone!  I apologize for the slow down in posting for a bit.  There's a reason it's called relic "hunting" and not necessarily relic "finding".  I've been focused on locating a few specific sites recently, which still seem to elude me.  So for a change of pace I went back to my roots and searched an old home site near Swepsonville, NC.  The owner told me it had been detected many times in the past - and he was right.  There weren't nearly as many non-ferrous tones as I'd expected.

 My recent finds in that area included a cool old pocket knife, brass tack or belt buckle, and this unknown brass piece.  I also found a small brass thimble, which is because I gave it away before taking these photos!  I really like the round brass buckle on the right.  It's most likely a sash buckle, dating from the mid 1800's to early 1900's.  The center bar is braised on and very sturdy, though the outside ring is quite a bit thinner.

I also went out again yesterday to a section of old road that I've been investigating with Jim from Silent Remnants.  We were disappointed with the results at what we imagined to be a promising location, but I still managed to find this small silver disc.  I believe it to be a coin based on the size and shape, though it is very thin and all detail is worn smooth.  What is it with me and finding smooth coins lately?  The square hole is not uncommon in older coins, as they were sometimes holed to be sewn into clothing or tied together to avoid losing them.  As far as age, I believe this to be my oldest silver coin to date - and here's why.

Modern dimes measure 17.9 mm in diameter.  But this particular coin is 18.8 mm.  This matches the diameter of early US dimes, which were larger and slightly lower in silver content.  When the seated liberty design was introduced in 1837, the silver content was raised, which required a small size reduction to maintain the total silver content (and thus value) of the coin.  Based on the diameter, the location it was found, and the square hole I believe this coin to be either a draped bust (1796-1807) or capped bust (1809-1837) US dime.  Of course, foreign silver coins still circulated in the United States well into the 19th century, so we'll never know for sure.  The Spanish 1 Real silver coin, for example, was very common in circulation during our nations first century, and approximately the same size.