All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is permissible –Allaah willing –to eat, grow and trade in mushroom, because in principle all things are permissible (until the opposite is proven).
Allaah Says (what means): {It is He who created for you all of that which is on earth.}[Quran 2:29] Furthermore, we are not aware of any evidence which prohibits it, and we do not know that it contains a religious prohibition that necessitates forbidding it.
Allaah Knows best.