Yes, pith is a Scrabble word!
...and is worth 9 points in Scrabble, and 9 points in Words with Friends
pith
Verb
1. Remove the pith from (a plant)
Noun
1. Soft spongelike central cylinder of the stems of most flowering plants
2. The choicest or most essential or most vital part of some idea or experience
What Scrabble words can I make with the letters in pith?
3 Letter Words
2 Letter Words