Rhubarb Surprise Cake

1 (18.25 ounce) box yellow cake mix
4 1/2 cups diced rhubarb
1 1/2 cups sugar
1 pint whipping cream (unwhipped)

Prepare cake mix according to directions on package. Pour into a 9 x 13-inch cake pan.

Mix together rhubarb and sugar. Mix until the rhubarb is coated with the sugar. Spread evenly over the cake. Pour unwhipped whipping cream over cake and rhubarb mixture.

Bake for 1 hour at 350 degrees F.