SLICE 1 cup strawberries; cut remaining strawberries in half.
ADD boiling water to gelatin mixes in large bowl; stir 2 min. until completely dissolved. Add enough ice to cold water to measure 2 cups. Add to gelatin; stir until ice is melted. Refrigerate 5 min. or until slightly thickened. Meanwhile, cover bottom of 13x9-inch dish with cake slices.
ADD sliced strawberries and 1 cup blueberries to thickened gelatin; stir gently. Spoon over cake. Refrigerate 4 hours or until firm.
SPREAD COOL WHIP over dessert. Top with fruit to resemble the flag, using strawberries for the stripes and remaining blueberries for the stars.