Yes, bud is a Scrabble word!
...and is worth 6 points in Scrabble, and 8 points in Words with Friends
bud
Verb
1. Develop buds
2. Start to grow or develop
Noun
1. A partially opened flower
2. A swelling on a plant stem consisting of overlapping immature leaves or petals
What Scrabble words can I make with the letters in bud?
3 Letter Words