First, I began in Maya by creating a low-poly basic mushroom shape.
I then imported it into Zbrush and began shaping it with the Move tool, added some texture to it and polypainted it. I then saved that mushroom as a Tool (ZLTool) and used the Append button to add it as another mushroom into my scene on a sub-layer. I repeated this process to add a third mushroom and used the move tool to bend and shape them a bit so each was unique.
Lastly I used the polynormals tool to assist with UV unwrapping, exported the texture map (colors) and the normal map (bump), then exported the mushroom meshes back into Maya so I could re-wrap the texture and bump on them and export as an FBX to Unreal.