Triboluminescence in wintergreen mints: https://www.youtube.com/watch?v=BckJfovkxOc

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).