For Salmon: Combine all ingredients except cracker crumbs. Spoon into a buttered 12x7 inch baking pan. Sprinkle cracker crumbs over top. Bake at 350 degrees F for 40 minutes or until firm in center. Cut into squares. Serve with mushroom pea sauce.
For Sauce: Cook mushrooms in butter or margarine for 5 minutes. Stir in flour and salt. Gradually add milk. Cook until smooth and thickened, stirring constantly. Stir in peas and pimento, cooking until hot. Spoon over salmon squares.