Prepare and bake the white cake mix according to the package directions. Fill 2- 8" or 9" round cake pans of a 9"x13" pan to bake your cake. Bake according to package directions.
Allow cake to cool completely before frosting with whipped topping. You may need more topping if preparing a 2 layer cake.
Top and decorate cake with blueberries, strawberries and raspberries. If using a 9"x13" cake you can decorate using the berries to form a US Flag design.
Refrigerate the cake for at least 1 hour before serving.