Preheat oven to 375 degrees.
Butter a 7 x 11-inch baking dish and pour in uncooked rice. In a medium saucepan, sauté green onions in butter until softened. Add mushrooms and continue to sauté until mushrooms are softened. Pour in chicken broth, sherry, salt and pepper. Bring to a boil, remove from heat and pour over rice in baking dish.
Cover baking dish, and bake in a 375-degree oven for 25 to 30 minutes or until rice is done.