Yes, ATTACHMENTS is a Scrabble word!

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

Is it a valid word?

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

a feeling of affection for a person or an institution
a supplementary part or accessory
a writ authorizing the seizure of property that may be needed for the payment of a judgment in a judicial proceeding
a connection that fastens things together
faithful support for a cause or political party or religion
the act of attaching or affixing something
the act of fastening things together

Also: fond regard.