1 (18.25 ounce) package yellow cake mix
1 (3 ounce) package instant vanilla pudding mix
1 (8 ounce) can crushed pineapple with juice
1 pint strawberries, sliced
1 pint blueberries, sliced
Preheat oven to 350 degrees F (175 degrees C). Grease and flour 2 9-inch round pans.
In a large bowl, mix the cake mix, pudding mix, pineapple and strawberries. Make sure each package contains the fruit. Fold in blueberries. Spread evenly into the prepared pans.
Bake in the preheated oven for 50 minutes, or until a toothpick inserted into the center of the cake comes out clean. Cool completely before cutting into squares.