Yes, CORNFLOWER is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, R 1, N 1, F 4, L 1, O 1, W 4, E 1, R 1.

Is it a valid word?

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

plant of southern and southeastern United States grown for its yellow flowers that can be dried
an annual Eurasian plant cultivated in North America having showy heads of blue or purple or pink or white flowers

Also: uvularia grandiflora, bachelor's button, centaurea cyanus.