Jedi and Sith alike collected artifacts through the eras. Palpatine was perhaps the greatest collector of his (or possibly any) time. He had a large collection of artifacts and treasures of all kinds which he kept all over the galaxy in his Skyhook, the Imperial Palace, and his storehouses and secret vaults. Grievous collected lightsabers from Jedi he defeated as trophies. Others like Boba Fett collected Mandalorian armors and weapons. Some, like Ace Azzameen, collected anything they personally found worthwhile. He kept various trinkets and items as mementos from his many adventures.