If Carmine Infantino had possessed a sense of humor, he’d have given us a few panels of Barry Allen, cursing under his breath, trying to cram his costume back into the ring at the end of a superhero gig.
The ring of Erreth-Akbe from the Earthsea books, although it was more like a torc than a ring, and had no magical powers; it was more a symbol of unity.
Oh, and from The Cat In The Hat Comes Back:
The water ran out
And then I saw THE RING!
A ring in the tub!
And, oh boy! What a thing!
A big long pink cat ring!
It looked like pink ink!
And I said, “Will this ever
Come off? I don’t think!”