I used to run a photo/camera shop in the 1990s and used to get a lot of people bringing in old rolls of b/w film that they had found in cameras. Usually VerichromePan or Panatomic-X- the occasional Agfa or Ilford roll, too. Old color films using outdated process (C-22, etc.) had to be sent to a special outfit in CO. I always got the customers to pay ahead of time, non-refundable, since I had no idea whether there was anything on the rolls and the B/W rolls I had to develop myself at home that night.
Got some amazing shots of Korean War era army base life, 1960s, 1970s local life, lots of bell bottom trousers, long hair, beards, mustaches, etc. Funny old cars, lots of fins and chrome. Occasionally pictures of long-dead family members, making some people start to tear up and sob when they saw them.
Speaking of old film, I occasionally use very old cameras with very old b/w film that's been frozen since the 1970s and 1980s. (I keep it in a spare refrigerator.) Mostly 122 size film in Kodak 3A Autographic and 3A Graflex cameras. Makes some interesting pics from those big negatives.