I was just browsing through the available kindle ebooks on Amazon and found a volume entitled "The Doom That Came to Dunwich" by Richard A. Lupoff, it appears to collect some of his mythos short fiction. It is currently available for free, the publisher is an imprint of the British Endeavour Press, a major ebook publisher who I've come to know for their re-issuing of 1970/80s naval fiction.
The contents are:
The Doom that Came to Dunwich (1997)
The Secret of the Sahara (2005)
The Turret (1995)
The Peltonville Horror (2001)
The Devil's Hop Yard (1978)
Documents in the case of Elizabeth Akeley (1962)
Brackish Waters (2005)
Adventure of the Voorish Sign (2005)
Nothing Personal (2010)
The Amazon page also includes a preview of the book with the editors introduction.