Grognardia on H.P. Lovecraft as reviser/collaborator:
Of course, Lovecraft being Lovecraft, he frequently rewrote nearly the entirety of the story he was merely supposed to revise. The result is something that should, in most respects, be considered a Lovecraft story. However, because he took seriously the notion that he was revising someone else's work, HPL did he best to retain as much of his client's ideas as possible, even when, in the final analysis, only the barest skeleton of non-Lovecraftian material can be seen in the revision. Thus, there's generally enough non-Lovecraftian concepts in these revisions to set them apart from the "pure" Lovecraft corpus, which is why some fans turn their nose up at them and treat them as "lesser" works.
I don't feel that way, since, as in the case of "The Mound," the story in question is massive in length -- over 25,000 words -- and filled with terrific Lovecraftian ideas. Written for a client by the name of Zealia Bishop, who lived in Kansas City, "The Mound" was begun sometime in 1929 and completed by 1930, but it did not see print until 1940, several years after Lovecraft's death. Even when it did appear in Weird Tales, it was a much abridged version, which probably contributed to the ill fame in which the story was held for many years. The full, original version of "The Mound" did not see print until 1989, in an Arkham House publication edited by S.T. Joshi and my reading of it a few years afterward convinced me that it is, in fact, a remarkable piece of work, one that ought to stand in the higher ranks of Lovecraft's fiction. [...]