What It Scores
YAFFS is a valid word in the tournament list this site uses. Tile values only, before any premium square: 14 in Scrabble and 14 in Words With Friends. The letters break down as Y4 A1 F4 F4 S1.
Words Made From The Letters In YAFFS
13 shorter words come out of these tiles. On a board that matters more than the long play, because a short word on a premium square often beats a long one on plain squares.
4 letter words (3)
3 letter words (5)
2 letter words (5)
Longer Words Containing YAFFS
YAFFS appears inside each of these, which is what makes it worth knowing as a hook.
Next: the Word Unscrambler for any letters at all. Full entry and definition at Merriam-Webster.