Looks British and judging is about the same size as their 3 shilling. Up to 1921 Canadian 5 cent pieces were made of silver and called fish scales due to their small size. Prized finds here. Happy hunting. <
My find is not as well documented as yours, but I'll post it anyway.
I found this tiny coin in California a few years ago. It's made of aluminum and is about the same size as your find. However, I didn't have the forethought to scan it with a dime for comparison. 8/
:congrats: Great Find! I found this 3-cent Silver in a farm field near the Hudson River, here in New York, at about 7 in depth. I never even knew these existed until I dug it. I thought it was a cuff button at first.