Yes, SLOES is a Scrabble word!

Letter values in Scrabble US: S 1, L 1, O 1, E 1, S 1.

Is it a valid word?

SLOES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

wild plum of northeastern United States having dark purple fruits with yellow flesh
a thorny Eurasian bush with plumlike fruits
small sour dark purple fruit of especially the Allegheny plum bush

Also: allegheny plum, alleghany plum, prunus alleghaniensis, prunus spinosa.