Saute mushrooms and green onions in butter until tender. Set aside. In large bowl, combine eggs, milk, salt, dry mustard, nutmeg and cheese. Fold in crawfish, mushrooms and onions. Pour mixture into pie shell. Bake at 400~ for 15 minutes. Reduce heat to 300~ and continue to bake for 30 minutes or until knife inserted in center comes out clean. Allow to stand 5 minutes before serving.