Look at that fextralife link. There are quite a few, the most powerful by far being the one you get from killing Crusher (the goblin at the camp you make kiss your foot). You can actually intimidate him to kiss your foot, wait for him to go piss alone at the bridge and kill him without aggroing anything else.
The ring gaves you a whopping +3m movement, basically double the wood elf racial, which is a ton.
The other ring I noticed is the one that gives you +1 arcana +1 religion from the Arcane Tower in the underdark.
The other big one is the one you buy from the vendor in the Myconid colony, it gives you the ability to not have penalty against obscured enemies. Helps casters a lot in the underdark. Another gives d4 to saving throws after you heal someone.
