1/2   pound         mushrooms
                    and sliced thin
3     tablespoons   melted butter or margarine
1 1/2 cups          soft white bread crumbs
2     tablespoons   minced chives
2     tablespoons   chopped parsley
1/2   teaspoon      dried tarragon or marjoram
1/2   teaspoon      salt
1/8   teaspoon      freshly-ground white pepper
1                   egg