She is always looking for novelty items to wear.
I think "novel" item makes more sense since we use adjective to modify a noun.
Am I right? Could I say "novel item"?
There is a big difference between a novelty item and a novel item.
Novelty | Define Novelty at Dictionary.com
See definition 3, that would be the common understanding of "novelty item."
If you mean she is always looking for new and unique things, then say "novel."