A friend of mine got a Euro with his change a while back.
The Mexican peso was the de facto currency of the United States for the first couple decades after the American Revolution.
Haven't gotten a Euro yet, but Over ten years of dumping excess pocket change in a "wish jar", I've got a baby food jar full of international currencies accidentally accepted. I also had family in northern Maine, until I was about 12, shops on either side accepted either currency, at least for small purchases, I think Canada was about 95 cents for a long time. I wouldn't try to turn customer service into a big political statement here.
I received a coin from the Cayman Islands a while back in change.