The Library of America selected a prime “R.E. Howard writes Lovecraft” story as their Free Story of the Week: “The Black Stone”. At the end of 2019 it proved to be at #5 in their end-of-year tally of their most popular stories.
Here it is in Weird Tales for November 1931.
The cover of this issue is also interesting. C.C. Senf provides a bristling black kittee that must have delighted the cat-loving Lovecraft when he saw the picture.