Yes, AMAZON is a Scrabble word!

Letter values in Scrabble US: A 1, M 3, A 1, Z 10, O 1, N 1.

Is it a valid word?

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

a large strong and aggressive woman
(Greek mythology) one of a nation of women warriors of Scythia (who burned off the right breast in order to use a bow and arrow more effectively)
a major South American river; arises in the Andes and flows eastward into the South Atlantic; the world's 2nd longest river (4000 miles)
mainly green tropical American parrots

Also: amazon river.