What It Scores
UMU is a valid word in the tournament list this site uses. Tile values only, before any premium square: 5 in Scrabble and 7 in Words With Friends. The letters break down as U1 M3 U1.
Words Made From The Letters In UMU
2 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.
2 letter words (2)
Longer Words Containing UMU
UMU appears inside each of these, which is what makes it worth knowing as a hook.
Next: the Word Unscrambler for any letters at all, and the two and three letter lists. Full entry and definition at Merriam-Webster.