Heads up! I’ll try to move this to a better host in the future.
I spent some time collecting CC0 textures. You may use them for any purpose:
Download from Drive (large, messy version, 5GB zip)
Download from Copy (unpacked, browse or download partially)
I only created some of the textures. I found the other textures on the interwebs, released under the CC0 license.
About Creative Commons Zero
These are only some of the categories:
Grunge and Paint
Manmade and Civilisation
Plants and Greenery
Tech, Future, Metal, Special, Weird