Help identifying less obvious 1950s good cards

[Tennis13]

Hey guys. I am meeting up with my dad this upcoming weekend and we are going to go through his cards to get some graded. I haven't looked through them in close to 10 years, and none of them are going to be like 9s and 10s, but he has a lot of good cards. Mostly from like 53-56. He has a few from 1952 as well and a few from 1957. No Mantles though.

I guess my question is aside from the obvious players that we will separate, are there any hard or hidden gem cards I should be on the lookout for? I know that crazy guy tried to corner the market on a random 1952 card. Aside from that, are there any sequences or hard to find cards of players that would make a John Doe valuable that I would not otherwise know? We have around 500 cards maybe, and we are going to send some in for grading.

I already know the one that will get the most groans: A Koufax rookie that literally looks like it was crumpled up and thrown in the garbage.