Yes, RATTAN is a Scrabble word!

Letter values in Scrabble US: R 1, A 1, T 1, T 1, A 1, N 1.

Is it a valid word?

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

climbing palm of Sri Lanka and southern India remarkable for the great length of the stems which are used for malacca canes
the stem of various climbing palms of the genus Calamus and related genera used to make wickerwork and furniture and canes
a switch made from the stems of the rattan palms

Also: rattan palm, calamus rotang, rattan cane.