In a dutch oven or pot, melt butter over medium heat. Add onion, celery, and mushrooms and cook until vegetables have softened and just started to turn brown, about 5 minutes.
Add garlic and cook for 1 minute more.
Add rice, salt, and pepper and cook until rice starts to look slightly transparent, about 2-3 minutes.
Stir in broth. Increase heat to high and bring to a boil.
Once boiling, add bay leaves, cover pot with a lid, and decrease heat to low.
Let rice simmer, covered, for about 15 minutes.
Once all liquid appears to have been absorbed, turn off heat and let sit, covered, for 5 minutes.
Discard bay leaves and fluff with a fork. Stir in parsley. Serve immediately.