Yes, GROUNDS is a Scrabble word!

Letter values in Scrabble US: G 2, R 1, O 1, U 1, N 1, D 2, S 1.

Is it a valid word?

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

your basis for belief or disbelief; knowledge on which to base belief
the enclosed land around a house or other building
a tract of land cleared for some special purposes (recreation or burial etc.)
a justification for something existing or happening
dregs consisting of solid particles (especially of coffee) that form a residue
the solid part of the earth's surface
a rational motive for a belief or action
the loose soft material that makes up a large part of the land surface
a relation that provides the foundation for something
a position to be won or defended in battle (or as if in battle)
the part of a scene (or picture) that lies behind objects in the foreground
material in the top layer of the surface of the earth in which plants can grow (especially with reference to its quality or use)
a relatively homogeneous percept extending back of the figure on which attention is focused
a connection between an electrical device and a large conducting body, such as the earth (which is taken to be at zero voltage)
(art) the surface (as a wall or canvas) prepared to take the paint for a painting
the first or preliminary coat of paint or size applied to a surface

fix firmly and stably
confine or restrict to the ground
place or put on the ground
instruct someone in the fundamentals of a subject
bring to the ground
hit or reach the ground
throw to the ground in order to stop play and avoid being tackled behind the line of scrimmage
hit a groundball
hit onto the ground
cover with a primer; apply a primer to
connect to a ground
use as a basis for; found on

Also: dry land, solid ground, terra firma, flat coat, primer coat, priming coat, run aground.