Yes, DAFFODIL is a Scrabble word!

Letter values in Scrabble US: D 2, A 1, F 4, F 4, O 1, D 2, I 1, L 1.

Is it a valid word?

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

any of numerous varieties of Narcissus plants having showy often yellow flowers with a trumpet-shaped central crown

Also: narcissus pseudonarcissus.