Yes, ELK is a Scrabble word!

Letter values in Scrabble US: E 1, L 1, K 5.

Is it a valid word?

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

large northern deer with enormous flattened antlers in the male; called `elk' in Europe and `moose' in North America
large North American deer with large much-branched antlers in the male
common deer of temperate Europe and Asia

Also: european elk, alces alces, american elk, cervus elaphus canadensis, red deer, cervus elaphus.