Read "Illusion" at The Eldritch Dark:
This short poem has an almost hallucinogenic quality. The progression from sunset (in the first line) to evening (the "graveyard-loving moon" in line six) leads us to end on the word "tomb", which adds a dramatic impact.
It's worth noting that in the Hippocampus Press edition of the poems, the last line is rendered:
Or cerements of a riven tomb.
Whereas The Eldritch Dark has:
Or silver cerements on a tomb.
The former seems much more powerful to me, since it creates the image of a violated tomb with the cerements scattered about, suggesting the work of a ghoul, a grave-robber, or something even more terrible.