Yes, mow is a Scrabble word!
...and is worth 8 points in Scrabble, and 9 points in Words with Friends
mow
Verb
1. Cut with a blade or mower
2. Make a sad face and thrust out one's lower lip
Noun
1. A loft in a barn where hay is stored
What Scrabble words can I make with the letters in mow?
2 Letter Words