Frank Babics: "Passengers" by Robert SIlverberg, from Orbit 4 ed. Damon Knight, Putnam, 1968
Jerry House: "Pigs is Pigs" by Ellis Parker Butler, from American Illustrated Magazine September 1905 and widely reprinted in magazines as well as other sites; issues of Ellery Queen's Mystery Magazine edited by Janet Hutchings and Alfred Hitchcock's Anthology edited by Cathleen Jordan
Tracy K: 100 Years of the Best American Short Stories edited by Lorrie Moore and Heidi Pitlor
George Kelley: Cream of the Crop: Best Mystery and Suspense Stories of Bill Pronzini edited by Bill Pronzini; Murder Most Medieval edited by John Helfers and Martin H. Greenberg
Todd Mason: World Literature Review, July 2024, International Horror in Translation, edited by Rachel Cordasco and Daniel Simon; Cordasco's website, Speculative Fiction in Translation;
Jeff Meyerson (in comments):"The Room with Something Wrong" by Cornell Woolrich from Detective Fiction Weekly (as "Mystery in Room 913"), 4 June 1938, edited by ?Kendell Foster Johnson; "The Skeleton Rides a Horse" by Toni Kelner (as by Leigh Perry), Ellery Queen's Mystery Magazine, September/October 2022, edited by Janet Hutchings
Kevin Tipple: "Girl's Night Out" by J. A. Jance (e-chapbook)
Plus:
Brian Busby: "Murder at Expo '67" (a novella-length excerpt "condensed" from Too Long at the Fair) by Janet Gregory Vernandel,as published in Cosmopolitan, October 1967, edited by Helen Gurley Brown, can be read here.
Steve Lewis: Analog Science Fiction/Science Fact, August 1967, edited by John W. Campbell, Jr.
"M Porcius": stories from Weird Tales, October 1939, edited by Farmsworth Wright; stories by Manly Wade Wellman, Ralph Milne Farley, a reprint by Robert E. Howard, and Kenneth Sterling and H. P. Lovecraft; four stories from Weird Tales by Mary Elizabeth Counselman
James Reasoner: Witchery Plus: A Weird Tales Trilogy by Keith Chapman; Selling the Wild West: Popular Western Fiction 1860-1960 by Christine Bold; Texas Rangers, May 1949, edited by ?Samuel Merwin (a guess); North•West Romances, Fall 1945; Lariat Story Magazine, August 1934, edited by J. F. Byne; Super-Detective Stories, May 1935, edited by Fred Armer; Thrilling Adventures, November 1943,edited by J. S. Williams
More to come!