you can certainly use image textures, plenty of places to get those, and such a wide variety that I won't even attempt to link any, you just need to look for ones that would work. Poliigon.com has some pretty nice looking image-scanned versions.
Otherwise if you need to use actual geometry, you can look for some displacement maps and do that right in keyshot in the material graph.
You could avoid the soil/moss being visible by modeling some sort of container or pot that they live in, sort of a raised bed garden look as well.
Either way, my biggest advice is to look for inspiration in other models, and take bits and parts of them to incorporate into your own.