My favorite dump cake is peach/pecan.
Grease 9x13" pan
1 (29 0z) can peaches with liquid into pan.
Sprinkle one one yellow cake mix.
1 1/2 cups melted butter drizzled over mix. Some just put slices of butter on top
Sprinkle brown sugar over top. Then chopped pecans
Bake 350 45min until brown and bubbly.