Thanks for posting this! Local legend is that the discovery of the 3-legged Buffalo was made by Ivan M. Fitzwater, a coin collector in Boise, Idaho. He operated a vending machine company and would go through all the coins. I have always assumed that he made the discovery in 1937 or shortly thereafter, but don't know that for sure. After he noticed the "missing" leg, he searched nickels in earnest and gathered up over a hundred of them, and then wrote an article for one of the national coin magazines of the day - Numismatic Scrapbook, probably. He sold the coins one at a time for years after he retired from his vending business in 1945 - I think his daughter may have ended up with the last one after he died in 1978. Some day I want to see if I can find a copy of the article he wrote.
John in ID