I am also a very small mushroom grower but not Psyolo Shrooms lol
I love Oyster Mushrooms and the Mycelium grow in a from me homemade Substrat of 50% Coco and 50% of Coffee grounds. When the Mushrooms are harvested the Mushroom compost is I believe a awesome way to grow a good healthy Marijuana plant full organic! But i don't know how much compost I can add to the Medium?
Here you can see how the compost looks like.

Here you can see how the compost looks like.