Rhubarb Upside Down Cake

4 cups chopped rhubarb
1 cup sugar
1 1/2 cups mini marshmallows
3 ounces strawberry Jello
1/2 cup chopped nuts
1 18-ounce white or yellow cake mix
Spread in greased 9" x 13" pan.
Sprinkle sugar over rhubarb.
Put marshmallows on top of above.
Sprinkle Jello and nuts on top.
Prepare cake mix and spoon over nuts.
Bake at 350° for 50 minutes.
Let cool 5 minutes.
Invert onto baking sheet.
Garnish with whipped cream.
Becky McCullough Knauth