Mine is a baseball signed by every member of the 1968 Detroit Tigers. My late father was a dentist who happened to have Jim Price as a patient. My dad got Jim to get every player and coach's autograph on the ball sometime near the end of the season and gave it to me on my ninth birthday. The names are a bit faded (after all it's 42 years old) but you can still clearly make them out although Earl Wilson's and Joe Sparma's are a bit faded.
I've had several offers to sell it but no way in hell I am ever parting with that ball. I was thinking about my dad today (he passed two years ago) and what a very cool gift that was.
PS: I also have a program from a game he took me to the next year agains the Red Sox. It was a doubleheader and I kept score during the game. The coolest thing about it is the full page ad for 1969 GTO Judge on the back cover!