I don't have much in the way of vintage Yankees memorabilia (just cards), but below are pictures of two of my favorite items--a game used ball from Game 6 of the 1952 World Series (Mantle hit his first World Series home run in this game) and a game used ball from Game 7 (Mantle hit his second World Series home run in this game).
I think these came from a ball boy or something, and there is another from game 2 out there with the same handwriting. Unfortunately, I don't own it yet and couldn't afford it even if I did have a shot at it. So, for now, I'll enjoy these.