Was Poe a member of any associations?
Literal associations would be hard to determine. He was not a member of the University of Virginia or West Point Alumni Associations; to the degree that they might have existed in the late 1820s, he dropped out of the former after a single semester and endeavored to get court-martialed out of the latter.
He was thematically associated with the Romantic literary movement in England, and likely the Gothic one as well, though his literary reputation in England gained little traction during his lifetime. And he was certainly a founder of the mystery genre (as the author of Murders in the Rue Morgue), which developed into an association of sorts (though again, Poe's membership in this was posthumous).
He developed rivalries and enmities within the literary community. He accused Henry Wadsworth Longfellow of plagiarism and in turn was accused of dissolute behavior by his rival Rufus Griswold (whose literary reputation has not endured the test of time). During his lifetime, the man was evidently not much of a joiner. After his death, everybody who could claimed him as a member; his apartment on the Range at the University of Virginia has been enshrined.