Lovecraft’s Secret Source for the Chthulu Mythos

H.P. Lovecraft claimed in a letter to Conan author Robert E. Howard that the Cthulhu Mythos was his own creation. Even diehard Lovecraft fans don’t buy that anymore. Lovecraft was a voracious reader (meaning he was poor and not exactly prolific) and was a hardcore fanboy before fanboys were a thing. He famously wore his influences on his sleeve (Dunsany, Poe, etc), but maybe there were some he kept a bit closer to his vest.