Yes, herb is a Scrabble word!
...and is worth 9 points in Scrabble, and 9 points in Words with Friends
herb
Noun
1. A plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests
2. Aromatic potherb used in cookery for its savory qualities
What Scrabble words can I make with the letters in herb?
3 Letter Words
2 Letter Words