I think wintergreen lifesavers emit light when you crunch them.
Quartz: https://en.wikipedia.org/wiki/File:Tribo.ogv
I've been able to see this by going into my driveway at night, by picking up some quartz gravel, jumping up and throwing the gravel down as hard as I can directly towards the ground (where it impacts other gravel).
That's how you get girls to agree to turn off the lights when playing post office.
I'm gunnuh try crushing an aspirin (acetylsalicylic acid) and see what happens. (ETA: My headache pills that have aspirin, acetaminophen, and caffeine, along with whatever binders, did not produce any light that my camera detected. That's the only aspirin I have and I'm only willing to sacrifice one of them. Oh well!)
ETA2: Wasn't able to get it to work by peeling a banana, crushing the inside, or crushing the peel, but I don't doubt it happened. Bananas probably vary a great deal. Thanks for the fun diversion, I haven't done an experiment like this in years.
Yep, and I probably should have mentioned, this was one of those giant, GMO-esque bananas, and it had a very thick, perhaps 1 cm skin, the interior of which was kinda fuzzy, such that peeling it was reminiscent of pulling apart velcro.