Yes, COCKSCOMB is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, C 3, K 5, S 1, C 3, O 1, M 3, B 3.

Is it a valid word?

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

garden annual with featherlike spikes of red or yellow flowers
a conceited dandy who is overly impressed by his own accomplishments
a cap worn by court jesters; adorned with a strip of red
the fleshy red crest on the head of the domestic fowl and other gallinaceous birds

Also: common cockscomb, celosia cristata, celosia argentea cristata.