Hello, darling, and welcome to Last Moon! We all hope you enjoy it here on the forum and ingame!
To answer your question, there is no exact list on "rare items", but there is the Wiki, located at the top of the forum, above the shoutbox. (However, it is not yet recently updated, but it still has many, many items on there). Many rare items are located there. Basically, if it can't be dropped or bought at Bazaar, then it's usually considered as a rare item. If you want to present what you'd like to trade, then go and make a new thread in the Game Market section on the forum. Happy hunting and trading!