Originally published in Weird Tales in 1926
This may be the cover least related to the story I have ever seen. Rather than being a sword-and-sorcery slash-fest, Pigeons from Hell is one of several regional horror stories by Howard set in the piney woods in or near the Ark-La-Tex region of the Deep South. It centers on a seemingly abandoned plantation and the legacy of terror the former slave-masters inflicted.
You can read the whole thing here.
Skull-Face originally ran as a three-part serial in Weird Tales in 1929….
Robert E. Howard clearly took his inspiration from the Fu Manchu books, but went far beyond that model to create a villain that could eat old Fu for breakfast. The guy with the skull-like face is first believed to be some sort of Chinese crime lord, then an ancient Egyptian, and finally a master sorcerer who should have gone down with Atlantis. He’s a guy who would have made a fine nemesis for Conan.
This story is in the public domain, and the full text is available here. Of course, it is one of the most racist stories I have ever read, but there it is.