It's been suggested that the Green Chapel of the Green Knight might be based on this cave.
.. the suggestion [was] initially advanced by Mabel Day ('Introduction to Sir Gawain and the Green Knight', EETS 210, 1940, p. xx) and developed and articulated in closer detail by Robert Kaske ('Gawain's Green Chapel and the Cave at Wetton Mill', Medieval Literature and Folklore Studies 1972, pp. 111ff.)..
..Having visited the site, I must admit that the case.. seems rather intriguing. A short distance from the stream a rugged knoll, overgrown with grass and weeds and with a crevice=like, rock-strewn cave about thirty feet long extending most of the way through it, tops a rather steep slope, separated from the stream only by a narrow gravel road. The knoll is faced at a distance of about three hundred yards across the stream by a forbidding-looking fissure-like hole leading into a deep, narrow cavern in the towering rock known as Ossom's Crag topping a steep hillside. Here, then, the 'Green Chapel' would be facing the hole in the rock whence the Green Knight so dramatically emerges...
Anyway after all that waffle, I think a more commonly held belief is that this part of the story is set at Lud's Church?
Ossum's Crag appears mainly to have been an occupational site, although human bone was recovered during excavation.
Flint and chert artefacts including blades and scrapers from the both the Mesolithic and Neolithic, prehistoric pottery, hearths and animal bones ranging from bison to vole.
Don Bramwell in his 1954 book 'Archaeology in the Peak District' suggested that a small raised ridge in the caves floor was used by flint knappers as an anvil stone.