Prep Time: 20 minutes (plus refrigeration)
SLICE 1 cup of the strawberries; cut remaining strawberries in half. Set aside.
STIR boiling water into dry gelatin mix in large bowl 2 minutes until completely dissolved. Add enough ice cubes to cold water to measure 2 cups. Add gelatin; stir until ice is melted. Refrigerate 5 minutes or until slightly thickened (consistency of unbeaten egg whites). Meanwhile, line bottom of 13- by 9-inch dish with cake slices. Add sliced strawberries and 1 cup of the blueberries to thickened gelatin; stir gently. Spoon over cake slices.
REFRIGERATE 4 hours or until firm. Spread whipped topping over gelatin. Arrange strawberry halves on whipped topping for strips of flag. Arrange remaining 1/3 cup blueberries on whipped topping for stars. Store in refrigerator.