Ornamented Death posted:

It sounds like those two collect pretty much all of his fiction and poetry, so you should be good to go. The only other thing I can think of is The Horror in the Museum, which collects stories Lovecraft edited and revised for other people. His level of involvement varies from simple edits to basically re-writing everything. I'm not sure if the stories in here are included in the two volumes you bought, but generally speaking these stories are kept separate from the main body of Lovecraft's work.

To go any farther with Lovecraft, you'd need to start picking up the pricier volumes annotated by Joshi, but frankly unless you're doing a major research paper on HPL, you don't need those.