Yes, STRETCHER is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, R 1, E 1, T 1, C 3, H 4, E 1, R 1.

Is it a valid word?

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

a wooden framework on which canvas is stretched and fixed for oil painting
a mechanical device used to make something larger (as shoes or gloves) by stretching it
a litter for transporting people who are ill or wounded or dead; usually consists of a sheet of canvas stretched between two poles
a stone that forms the top of wall or building

Also: coping stone.