Yes, CHATTERBOX is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, A 1, T 1, T 1, E 1, R 1, B 3, O 1, X 8.

Is it a valid word?

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

orchid growing along streams or ponds of western North America having leafy stems and 1 greenish-brown and pinkish flower in the axil of each upper leaf
an obnoxious and foolish and loquacious talker

Also: stream orchid, giant helleborine, epipactis gigantea.