Actually, Howard wrote several "contemporary" (meaning set in the '20s) Cthulhu cycle stories as well. One of their favorite tricks was to reference a common "tomes of forbidden lore" such as "
Nameless Cults by Von Juzt" and of course "The
Necronomicon" in order to give the books the sound of legitimacy.
It's hard to imagine two more different guys -- Howard was a rough-and-ready Texan and an accomplished boxer, while Lovecraft was a retiring and prone-to-sickliness New England scholar. But they both admired each other's work greatly and corresponded a great deal, although they never met in person.
-The Gneech