Yes, MAYFLOWER is a Scrabble word!

Letter values in Scrabble US: M 3, A 1, Y 4, F 4, L 1, O 1, W 4, E 1, R 1.

Is it a valid word?

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

the ship in which the Pilgrim Fathers sailed from England to Massachusetts in 1620
low-growing evergreen shrub of eastern North America with leathery leaves and clusters of fragrant pink or white flowers

Also: trailing arbutus, epigaea repens.