I have found a few foreign silver coins. I always assume that they were part of coin collection, and somehow got lost. Smittyman says that kids took them to show-n-tell, and then lost them on the way home.
That is a very unusual find and the first time I have seen a coin like that posted.
Living in NYC affords me the opportunity to find more coins from foreign lands
than I guess you would find in other parts of the country. On one hunt this
year, I found 42 coins on a single hill. The only one that was Silver, was a
1900 Canadian Dime.
Congrats to your buddy on an excellent recovery.