Sauté livers in butter in a large skillet 5 to 6 minutes. Remove livers; add mushrooms and onion to pan drippings. Sauté until onion is tender. Stir in flour and salt. Add wine, parsley, and Worcestershire sauce; bring to a boil. Reduce heat, and simmer 3 to 5 minutes. Add livers; cook 5 minutes over medium heat. Spoon liver mixture over toast points. Serve warm.