general

https://opengameart.org/content/abstract-noise-pack
https://opengameart.org/content/seamless-abstract-pack
https://opengameart.org/content/abstract-texture-pack
https://opengameart.org/content/tiny-texture-pack-1
https://opengameart.org/content/tiny-texture-pack-2
https://opengameart.org/content/tiny-texture-pack-3
https://opengameart.org/content/700-noise-textures
by Screaming Brain Studios, CC0

https://opengameart.org/content/40-procedural-textures
https://opengameart.org/content/procedural-texture-pack
by drummyfish, CC0


lava:
mixed with
https://opengameart.org/content/molten-rock-like-thing
by Prime_8, CC0

mixed with some own textures, CC0