The Spawn of Cthulhu is an interesting anthology of Cthulhu fiction. It's a bit difficult to find these old anthologies nowadays, so I'm glad that I managed to buy this book.
The best short story in this anthology is H. P. Lovecraft's The Whisperer in Darkness. It's one of the best Cthulhu stories ever written, because it's a weird, fascinating and creepy story about the backwoods of Vermont. It's an excellent blend of horror and science fiction.
I also liked Clark Ashton Smith's The Tale of Satampra Zeiros, Robert E. Howard's The Children of the Night and August Derleth's The Return of Hastur. The other short stories were also good, but none of them can be compared to Lovecraft's story.
Lin Carter's notes and comments were interesting. They provided good information about Cthulhu mythology.