These artifacts appear among loot. Any encounter awarding loot can include some of these as well. The Aldvari was one of the ancient races that once lived on Sryth. More details at World of Sryth. These items can be exchanged in the Westgard Library in Talinus for Battle Markers. Keep in mind that the exchange is in bulk, all at once, so if you want to save some of them (most likely, 12 Common ones for Hawklor's Plume Merchant) store them in one of your Dwellings.