Preheat oven to 350 degrees. Dump two 29 oz cans of peaches (with 1/2 of the total juice drained) into skillet. Sprinkle (2T) brown sugar and (1 t) cinnamon evenly over peaches. (there will still be a lot of juice in pan, but the juice will be absorbed by the cake mix).
Sprinkle 1 box dry yellow cake mix over peaches. Spread out evenly.
Thinly slice (1/2 stick) butter, and distribute butter slices on top of cake mix.
Cover if cooking over fire, can bake without a lid (that's what I do). Cook for 60 minutes, or up to 90 depending on campfire temperature. Top should be golden brown and peach juices bubbly.
Remove and serve immediately. Serve with vanilla ice cream or whipped cream if desired.