I called the items for the wrong name then. I mean salvage items that you give to collectors like Stone Summit Badges, Enchanted Lodestones, Grawl Necklaces... Do you keep any of them or just sell/salvage?
There are some that are worth keeping. They can net you superior armor early on (such as the alternate appearance superior armor in Pre-Searing) or you can get a free set of armor that is slightly stronger than the one that you could have crafted in a nearby town. But the collector's items vary.
Personally, I sell them for a small amount of gold, until I stumble across a collector. Since they usually ask for items that can be found from nearby monsters, I simply purchase the necessary amount of collector's items from my party members.