Yes, QUID is a Scrabble word!

Letter values in Scrabble US: Q 10, U 1, I 1, D 2.

Is it a valid word?

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

the basic unit of money in Great Britain and Northern Ireland; equal to 100 pence
something for something; that which a party receives (or is promised) in return for something he does or gives or promises
a wad of something chewable as tobacco

Also: british pound, british pound sterling, pound sterling, quid pro quo.