Oldest coin yet

I've been craving to find an old coin from the 1800's. Our oldest coin so far is a quarter from 1956. Mary's mom Pat's friend Shelia's mom has property in Niagara-on-the-Lake. Through a series of phone calls we gained permission to detect her property. Mom picked us up in her van and the three of us went over. The yard was smaller than I hoped for but undaunted we systematically scanned that yard while mom talked to Shelia's mother. We found six things scanning both the front, back and boulevard: Nails, beer caps, bits of aluminium siding, chicken wire, a 1989 penny and lastly the OLDEST COIN YET!!!
I knew when I first plunked it from the ground that it was exceptional. As I wiped the dirt away I was greeted by King George's face. Recognizing the size of the coin as a nickle I cleared the other side to discover the date of 1938. Now perhaps we've received and older coin in our change from Tim Horton's in the past but to us this is a major find. Though our daily total is only 6 cents this was a great day and I glad we could get out.