Yes, AGAVE is a Scrabble word!

Letter values in Scrabble US: A 1, G 2, A 1, V 4, E 1.

Is it a valid word?

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

tropical American plants with basal rosettes of fibrous sword-shaped leaves and flowers in tall spikes; some cultivated for ornament or for fiber

Also: century plant, american aloe.