Prepare cake mix according to directions on box, and bake in two layers.
Remove cakes from pans. Clean pans. Return cool cake to pans. Pierce cake with meat fork 1/2 inch apart.
Mix strawberry Jell-O and 1 cup boiling water; pour over first layer.
Repeat with blueberry Jell-O for second layer. Refrigerate 3-4 hours.
Dip pans in hot water to loosen cake. Put layers atop each other, using Cool Whip for filling and frosting.
Decorate top with small American flags.
Servings: 8