Yes, LYCHEES is a Scrabble word!

Letter values in Scrabble US: L 1, Y 4, C 3, H 4, E 1, E 1, S 1.

Is it a valid word?

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

Chinese fruit having a thin brittle shell enclosing a sweet jellylike pulp and a single seed; often dried

Also: litchi nut.

Not playable in Scrabble US: LITCHEE, LEECHEE.