Besides the 10 essentials, bring:
1. A tent
2. sleeping bag
3. sleeping pad (insulate you from the ground)
4. eating utensils (bowl, plate, knife, fork, spoon); unless provided by the troop
5. Toiletries (toothbrush, toothpaste, comb/brush, etc.)
6. insect repellent
7. sunscreen
8. a hat
9. jacket
10. extra clothes
11. camera
12. towel
13. book or magazine
14. flashlight with extra batteries
Check your son's Scout Manual for a list of stuff to take on overnight camp outs.