Yes, LEGUME is a Scrabble word!

Letter values in Scrabble US: L 1, E 1, G 2, U 1, M 3, E 1.

Is it a valid word?

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

an erect or climbing bean or pea plant of the family Leguminosae
the fruit or seed of any of various bean or pea plants consisting of a case that splits along both sides when ripe and having the seeds attach to one side of the case
the seedpod of a leguminous plant (such as peas or beans or lentils)

Also: leguminous plant.