[Kawika]

Emmett Eugene Munsell
Throws Right
Born: March 1, 1889 in Eminence, MO USA
Died: December 1974 in Longview, TX USA
Hick Munsell was a right-hander who played six years in the Texas League, twice becoming a twenty-game winner.
Munsell had one of the biggest mound turnarounds in minor league history. After losing 27 games in 1914, splitting time with Austin and San Antonio, he rebounded by winning 25 with San Antonio in 1915.
Munsell was invited to spring training with the 1912 New York Giants but had a disagreement with John McGraw about throwing curve ball after curve ball in an intrasquad game; the argument resulted in a fist fight on the mound and Munsell's release that same day.

I couldn't find any stats in the Baseball Encyclopedia for an ML appearance by Munsell so maybe his one day in the majors was the time he duked it out with McGraw. He had a solid minor league record, had his picture on a few baseball cards, and your son will be able to say that he shook the hand that shook the hand that punched John McGraw. All very cool. Good luck in securing a card. With a bit of persistence it seems quite doable.