I was delivering a fine lecture to Phil on this subject only last night. THE RING AND THE RINGS - Wagner vs. Tolkien:

Tolkien refused to admit that his ring had anything to do with Wagner’s. “Both rings were round, and there the resemblance ceased,” he said. But he certainly knew his Wagner, and made an informal study of “Die Walküre” not long before writing the novels. The idea of the omnipotent ring must have come directly from Wagner; nothing quite like it appears in the old sagas. True, the Volsunga Saga features a ring from a cursed hoard, but it possesses no executive powers. In the “Nibelungenlied” saga, there is a magic rod that could be used to rule all, but it just sits around. Wagner combined these two objects into the awful amulet that is forged by Alberich from the gold of the Rhine. When Wotan steals the ring for his own godly purposes, Alberich places a curse upon it, and in so doing he speaks of “the lord of the ring as the slave of the ring.” Such details make it hard to believe Tolkien’s disavowals. Admit it, J.R.R., you used to run around brandishing a walking stick and singing “Nothung! Nothung!” like every other besotted Oxford lad.