Two stories and the sonnet cycle about The Necronomicon, Lovecraft's fictional book of hidden occult knowledge.
History of the Necronomicon was written in 1927 but not published until 1938, after Lovecraft's death. It describes the origins of the fictional book of the same name: the occult grimoire Necronomicon. The Necronomicon is a piece of pseudobiblia which plays a large role in much of Lovecraft's work.
The Book is an unfinished short story that was written in 1933. It was first published in the journal Leaves, in 1938, after Lovecraft's death.
Fungi from Yuggoth is a sonnet cycle of 36 sonnets by H. P. Lovecraft. Most of the sonnets were written in the nine day span between December 27, 1929 and January 4, 1930; thereafter individual sonnets appeared in various magazines such as Weird Tales.
The cycle begins with the discovery and theft of an ancient book of esoteric knowledge (The Necronomicon, though it is never actually named) that seems to allow one to travel to parallel realities or strange parts of the universe. The poems that follow, though disparate in themselves, detail a succession of visions that a reading of the book releases.