I made an red, white & blue strawberry poke cake last year! 
Ingredients:
1-2 boxes of white cake mix
1 packet of strawberry jello
1 container of fresh strawberries
1 cup of blueberries
Directions:
Make cake as directed on the back of the box for a 9″×13″ pan.Let the cake cool for 20 minutes and “poke” the cake with a large fork until the entire surface of the cake is covered. Mix together the boiling water and Jell-o until the Jell-o is completely dissolved. Pour in the cold water and mix well then pour over the cake. Cover the cake with plastic wrap and refrigerate for three hours. Spread cool whip on top of cake. Top with strawberries and blueberries and keep in the fridge until ready to serve.