Yes, LING is a Scrabble word!

Letter values in Scrabble US: L 1, I 1, N 1, G 2.

Is it a valid word?

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

water chestnut whose spiny fruit has two rather than 4 prongs
common Old World heath represented by many varieties; low evergreen grown widely in the northern hemisphere
elongated marine food fish of Greenland and northern Europe; often salted and dried
American hakes
elongate freshwater cod of northern Europe and Asia and North America having barbels around its mouth

Also: ling ko, trapa bicornis, scots heather, calluna vulgaris, molva molva, lota lota.