In A Large Skillet, Brown The Onion And Brown Rice In 2 Tablespoons Of Butter. Add Wild Rice, Bouillon, Water, Salt And Pepper To Taste. Bring To A Boil, Reduce Heat And Simmered Covered For 45 Minutes. Simmer Until Liquid Is Absorbed. Saute Mushrooms In Remaining Butter. Stir Into Rice Mixture And Bake For 30 Minutes In A Buttered Dish At 350 Degrees.