Yes, LINDEN is a Scrabble word!

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

Is it a valid word?

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

soft light-colored wood of any of various linden trees; used in making crates and boxes and in carving and millwork
any of various deciduous trees of the genus Tilia with heart-shaped leaves and drooping cymose clusters of yellowish often fragrant flowers; several yield valuable timber

Also: linden tree, lime tree.