Sauté mushrooms in 1/4 cup plus 2 tablespoons butter in a large skillet. Remove mushrooms; set aside. Reserve butter in skillet. Add rice to skillet; cook over medium heat, 5 minutes, stirring constantly. Stir in mushrooms, green onion, and broth. Spoon mixture into a lightly greased 2-quart casserole. Cover and bake at 350° for 1 hour. Uncover and bake an additional 15 minutes.
Sauté almonds in remaining butter. Stir into rice mixture, and serve immediately.