Sauté beech mushrooms in a pan until soft. Remove from pot and set aside.

In the same pot, add diced celery, salt, garlic powder, and black pepper and sauté until golden.

Once celery is golden, add in rice and water, stirring occasionally.

Bring rice to a boil, then reduce to a simmer and cook, covered and stirring occasionally, until all the liquid is absorbed, about 25 minutes.

When the rice has absorbed all the liquid and is soft, take off heat. Stir in beech mushrooms.