Here is another short poem from Clark Ashton Smith (CAS) that was unpublished in his lifetime. Since it's not available on The Eldritch Dark, here's the complete text:
Hued with verdigris and cream,
Buttress the chambered gloom.
This haiku presents a beautiful portrait of the dense alien environment of a limestone cavern, one of the true wonders of our planet's geology. The closing phrase "the chambered gloom" is a perfect expression of what it feels like to stand in such an incredible (yet haunting) space.