Prepare cake mix according to directions in a 9x13 pan.
Cool completely on wire rack over sheet of wax paper.
Poke cake with handle of wooden spoon at 1 inch intervals.
Dissolve jello in boiling water.
Slowly drizzle over cake to allow jello to seep into the holes.
Chill one hour.
Place pudding in medium sized bowl. Add milk and stir until thick.
Fold in 1 cup of the whipped topping and 1/2 cup of the blueberries.
Split the cake horizontally in half. Fill with pudding mixture.
Spread 2 cups of topping over the top and sides of the cake.
In the upper left hand corner of the cake, arrange the remaining blueberries to represent the stars on the American flag.
Arrange the strawberries and bananas in rows to represent the stripes in the flag, starting and ending with the strawberries.
Place the marshmallows around the edge of the entire cake, making a border.