Discard the casings from 1/2 pound Italian sausages and cook until barely pink; finely chop. Add 1 cup finely chopped onion and 1/2 cup finely chopped bell pepper to the pan and cook until softened. Stir in the sausage, 2 tablespoons Italian breadcrumbs and 1/4 cup chopped parsley; season with salt and pepper. Fill 16 white stuffer mushrooms. Bake in a 375 degrees oven for 15 minutes.