Stars And Stripes Celebration Cake

One hour ahead: Heat oven to 350 degrees. Grease two 15 1/2 x 10 1/2 x 1″
jelly-roll pans; line with wax paper; grease paper. Prepare cake batter
according to package directions, working with one package at a time. Spread
batter in prepared pans; bake 15 to 20 minutes until wooden toothpick
inserted in center comes out clean. Invert cake layers onto wire racks;
peel off paper; cool. In medium size bowl, toss banana slices with lemon
juice. Pour off excess juice; set bananas aside. Slice about 24 well shaped
strawberries lengthwise in half; reserve for top of cake. Coarsely chop
remaining strawberries; set aside. In large bowl with electric mixer at
high speed beat cream until soft peaks form; gradually beat in sugar until
stiff. Spoon half whipped cream into second bowl; fold in chopped
strawberries. Set both creams aside. Place one cake layer on large serving
platter; tuck strips of wax paper under cake to keep platter clean. Using
spatula, spread strawberry cream over cake; top with second cream cake
layer. Spread plain cream over top and sides of cake; carefully remove wax
paper strips. In top left hand corner of cake, using tip of sharp knife,
mark 7 1/2 x 5″ rectangle. Place blueberries in even rows in the rectangle
to form stars of the flag. To from stripes, alternate rows of strawberries
and bananas, overlapping fruit in each row as necessary. Chill until
serving time, up to 2 hours. Cut into 2 x 1 1/2″ pieces to serve.