Sort:  

I don't have oak forests. But I found two reishi on an old spruce stump in the forest.
It is possible to grow, but such mushrooms will not be as strong as forest ones.

Actually they prefer half dead, dying or even totally dead trees. I have also once found them in the more higher forest where no oak grow, on an old pine or cedar stump...

The stump on which I found Resha was a complete rotten wreck))

Also possible!