Thank you for this richly illuminating symposium. I'd like to contribute a few comments to the discussion:
-- In exploring the theme of decapitation, several pertinent mythic examples were mentioned: the beheading of the Medusa, the annual harvest beheading and spring renewal of the Corn King, and so on, but a very significant one went unnoticed. A major theme in the story of Gawain and the Green Knight -- as observed during the symposium -- is the tension and interplay between a green nature paganism and medieval Christianity. In the Judeo-Christian tradition, at least three significant decapitations occur: David, after dispatching Goliath with his slingshot, cuts off the giant's head; Judith decapitates the enemy general Holofernes; and, most important for the Gawain and Green Knight myth, there's the example of John the Baptist. John is a wild man; he lives in the desert wilderness but his domain is the running water of baptism; he dresses in the skin of a wild animal; he eats locusts and honey. He's primal and atavistic; he personifies Nature and is an outlier. At the same time, he's the cousin of Jesus -- of the Christian church -- and he's explicitly identified as a precursor of the Messiah; he's the one preparing the way for Jesus, as he announces to the crowds. When John the Baptist, this wild man of Nature (the realm of the Green Knight as well) and precursor of Christianity (the Arthurian realm) , is imprisoned and Salome is offered whatever she wishes, she requests the head of John on a platter -- and John the Baptist is decapitated. This New Testament story offers intriguing parallels to themes in the tale of Gawain and the Green Knight.
-- The etymological connection between the word "game" and the Old English "gome" (man) was noted in the conversation, yielding a pun on "game" and "man" and underscoring the themes of play and of coming to a mature masculinity, but additional meanings went unmentioned: "game" as that which hunters pursue (in the myth and in the movie Bertilak daily pursues the game animals of boar, stag, and fox), and "game" meaning readiness, as in "sure, I'm ready, I'm up for it, I'm game." Thus, at the end of the movie, when Gawain kneels before the Green Knight to receive what he assumes will be his beheading, if instead of saying "I'm ready" he had said, "I'm game," it would have incorporated all four meanings of the word: "I'm finally at play here, I'm a man now, I'm willing to be prey, and I'm ready."
-- Eliot's "The Wasteland" was mentioned in passing during the discussion, but never fully addressed. It's a substantial topic, and too vast to fully investigate here, but it's worth noting briefly that Eliot incorporates the myth of the Fisher King and the wasteland in a post-World War One urban crisis of falling European civilizations, and in doing so he utilizes several images that we see in the "Green Knight" movie: dead trees, dead land, an empty chapel. During the symposium a connection between the Green Knight and Thor was discussed, and the accompanying Thor-like motif of the thunder -- in Eliot's "Wasteland" the thunder also speaks (in Part V., "What the Thunder Said." Incidentally, the thunder also speaks in Tennyson's Arthurian poem, which may have influenced Eliot). Eliot also moves beyond Eurocentrism to incorporate references to Hindu Upanishads and to Buddhism, particularly in Part III, "The Fire Sermon" (an explicit reference to the Buddha's sermon of the same name) and, again, in Part V, when the rain finally comes and Eliot gives invocations in Sanskrit, culminating with "Shantih. Shantih. Shantih."
-- Incidentally, in regard to Buddhism, during the symposium numerous examples of mythic figures associated with the color green were cited. It may be worth adding the example, from Tibetan Buddhism, of the bodhisattva Green Tara.
-- One final observation about the theme of "wasteland" -- it's interesting to note the pun on "waste" and "waist" as it pertains to Gawain; moving through a wasteland, his amulet is a green sash he ties around his waist. The sash around the waist rhymes thematically with the blindfold around the eyes of Morgan and of the old woman, the blindfold which enables second sight or true vision, while the sash around the waist girdles the anatomical locus of fecundity.
-- Thanks again!