Ending June 16th, RR Auction has a typed, signed letter from Tolkien to Andrew Schiller dated June 22, 1957 (Chronology, p. 536) that discusses Sir Gawain and the Green Knight.

In fine condition. Accompanied by the original mailing envelope.

Estimate: $3000+

https://www.rrauction.com/auctions/lot ... yped-letter-signed/?cat=0