Thanks, Jimmy! As Jimmy stated, this thread is definitely in my wheelhouse.
Here are some of my all-time favorite tickets and scorebooks in my personal collection:
1) Ticket stubs from the last game of HOF'ers Sandy Koufax's 382 K Cy Young season in 1965 and Nolan Ryan's ML record 383 K season in 1973.
Koufax still holds the NL and lefty hurler record for a single season, although (future HOF'er) Randy Johnson got close a couple of times.
Nolan Ryan is a collecting focus of mine and I am biased, but IMHO I believe that his 383 K record is more impressive because he did it in the AL during the 1st year of the DH era (1973). In 1973 American League pitchers didn't have the luxury of padding their strikeout totals by pitching to other hurlers.
Note: Had a rainout in KC not washed out one of Nolan's starts in September, he might have possibly struck out 390-400 batters in 1973. Additionally, he was scheduled to pitch the final game in Anaheim in 1973, but still managed to break Koufax's record in spite of pulling a hamstring in the 383 K game. I was actually at this game and saw Ryan set the ML record.
2) Scorebooks/programs from Sandy's 382 K game and Nolan's ML record 383 K game
3) Dated parking pass from Ryan's 383 K game