We went to four used bookstores in one day recently. (One in Tullahoma, three in Murfreesboro, both here in Tennessee, somewhere between one and two hours away from where we live.)
"The Book Shelf" in Tullahoma consists entirely of donated books, and raises funds for literacy. Staffed by older women (volunteers?) and pretty well organized.
"The Happy Book Stack" in Murfreesboro also had vinyl records, comic books, manga, etc. Lots of tiny children came in (not my favorite company, frankly.) Run by a fellow best thought of as a "dude."
"The Grumpy Bookpeddler" in Murfreesboro was very nicely organized, and had a HUGE science fiction and fantasy section. The majority (but not all) of the SF/fantasy books listed below came from this place. Run by an older gentleman.
"Crying Cat Books & Records" in Murfreesboro had, of course, vinyl records, DVD's, CD's, and both new and used books. Run by a young woman. Best thought of as a "hip" place.
My better half got about as many nonfiction/intellectual books as the SF/fantasy/and other books I got, listed below. I don't recall exactly which book I got where, but, as said, most were from The Grumpy Bookpeddler.
Magazines:
Amazing, March 1988, November 1990, and January 1996. (There was also one from the 1970's but it had a badly damaged cover and consisted mostly of old reprints.) There were also tons of The Magazine of Fantasy and Science Fiction and Analog from the 20th century. We already own all of the former, and was not extremely interested/was overwhelmed by the latter.
Hardcover nonfiction:
The Ape-Man Within (1995) by L. Sprague De Camp. The SF/fantasy writer suggests that our primordial ancestors gave us the characteristics that explain why we mess things up so badly.
Hardcover science fiction/fantasy:
From This Day Forward (1972) by John Brunner. Collection.
Unicorn Mountain (1988) by Michael Bishop. Fantasy.
The Coming (2000) by Joe Haldeman. SF.
The Businessman: A Tale of Terror (1984) by Thomas A. Disch. Dark fantasy/black comedy.
Maps in a Mirror: The Short Fiction of Orson Scott Card (1990) by You Know Who. Often split into four smaller books, this big volume is said to contain "virtually" all his short fiction from the beginning to the date of publication.
Large softcover SF/fantasy:
The Annotated Wizard of Oz (Centennial Edition) (1900/2000) by L. Frank Baum, annotations edited by Michael Patrick Hearn. A big, lovely book.
Zero History (2010) by William Gibson. Borderline SF/technothriller, the last book in a very loosely related trilogy after Pattern Recognition (2003) and Spook Country (2007), which I read a while ago.
Red Moon (2018) by Kim Stanley Robinson. SF.
Paperback Sf/fantasy:
The Man Who Awoke (1933; 1975 reprint) by Laurence Manning. Supposed to be a classic of pre-Campbell SF.
The Jewels of Aptor (1962; revised/expanded 1968) by Samuel R. Delany. His first novel. SF.
The Eleventh Commandment (1962; revised 1970) by Lester del Rey. SF. Overpopulated future world ruled by a Church.
Ice (1967) by Anna Kavan. New Wave? Slipstream? Surrealism?
The Butterfly Kid (1967) by Chester Anderson. Hippie SF.
Tool of the Trade (1987) by Joe Haldeman. SF.
Science Fiction: The Best of 2001 (2002) edited by Robert Silverberg and Karen Haber. Anthology.