Over on ancient-origins.net, they give us "Magical Rings and Their Mystical Powers" here. These are all real world items said to have possessed mystical or magical powers and worn by such luminaries as King Solomon, Charlemagne, and Genghis Khan. I particularly love that archaeologist Howard Carter wore a ring believed to be enchanted in ancient times to protect the wearer from curses, like those one might get exploring a mummy's tomb.
Also, on historyextra.com, they share a nice collection of photos of various items from the Staffordshire Hoard here. Although they are misshapen from time and environmental conditions, and not perfectly restored, you can certainly see why these were set aside as treasures.
Finally, on ultanya.com, the Gran DM offers up some wonderful "Ravenloft Trinkets" in the form of a randomized table here. These were created with The Curse of Strahd in mind but is more versatile than that, so bookmark and save this for your tabletop RPGing!