A cool way to add moss to a mess with texture painting. Click the link for the real-time version: https://youtu.be/HbMM0uf3IEs?si=HrYW3jFiEM7AZFqy
As a disclaimer, this technique gave me trouble the first time I tried it and there are several steps within the process that were condensed for sake of time.
Additionally, 'influence' won't appear as an option until a texture is chosen in the Particles tab (particle system, Textures -- select a texture). Then it should appear. Apologies if that was a bit confusing in the video.
2023