The first ring i found is by Seyda Neen easy to get and it Increases Intelligence and Willpower. First go to the Seyda Need Tradehouse. Stand in front of the door and Go North West till you reach the ocean head north till you find a tomb Called Samary's Ancestral tomb or something like that. It's a small tomb with few undead monster's or if your a high level it wont be as easy as being level 1. Follow the Rooms till you find a Urn that it traped It is Fire dmg and it can kill ya. the ring is in there.
Second ring is located in Seyda Need Go to the Silt Strider and head north till you reach a cave. There are Two ways to reach this Ring ill tell ya the fastest way. First when you go in there is a Enemy Kill her. Second proceed to the next room. Go up the staires, when reached the top head to your right and follow the passage. You should find some mushrooms. There will be a Netch Pauldron Keep following the tunnel till you find some more mushrooms there will be the outher Pauldron, And a Ring Called Thiefs Ring. Agility, Speed, And personality +5 for 30 sec.
Third ring is located in Gnisis. Start at the Silt Stridder and head east till you reach Fort Darius Keep going east a little till you find a road sign Face South and Jump in the river and swim South Till you reach Falas Ancestral Tomb Take the Second Door on the left and follow the Way down anouther urn that is traped. This time it's Paralyze. This ring Gives you 30 Resistance to Fire,Cold, and Lightning.