Hey Joe...
I need a George Sisler endorsed Mitt for my collection... Any chance that you'd trade that one for a nice Jimmie Foxx model?
Haha... couldn't resist! I think we all have a few "untouchable" pieces, but that story is indeed hard to beat.
FWIW, my first-ever piece of baseball memorabilia was the white version Giants Pennant below, given to me at age 5 (by my Dad). The very first of way too many pennants, and the root of subsequent obsessive compulsive disorder.