Yes, KINGCUPS is a Scrabble word!

Letter values in Scrabble US: K 5, I 1, N 1, G 2, C 3, U 1, P 3, S 1.

Is it a valid word?

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

swamp plant of Europe and North America having bright yellow flowers resembling buttercups
any of various plants of the genus Ranunculus

Also: marsh marigold, meadow bright, may blob, water dragon, caltha palustris, butter-flower.

Not playable in Scrabble US: BUTTERFLOWER, GOLDCUP.