Yes, dung is a Scrabble word!
...and is worth 6 points in Scrabble, and 9 points in Words with Friends
dung
Verb
1. Fertilize or dress with dung
2. Defecate; used of animals
Noun
1. Fecal matter of animals
What Scrabble words can I make with the letters in dung?
3 Letter Words
2 Letter Words