Yes, LAPPET is a Scrabble word!

Letter values in Scrabble US: L 1, A 1, P 3, P 3, E 1, T 1.

Is it a valid word?

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

a fleshy wrinkled and often brightly colored fold of skin hanging from the neck or throat of certain birds (chickens and turkeys) or lizards
a small lap on a garment or headdress
medium-sized hairy moths; larvae are lappet caterpillars

Also: lappet moth.