Not only does this very famous Poe story contain a (very little) bit of mathematics in the form of a probabilistic approach to cryptography and a geometric description of the treasure hunt on the ground (as pointed out by William E. Emba), it is especially notable for the fact that it takes place here in Charleston : )
The entire story is available online...follow the link above or below.
Summer MacDermott has written to let me know about another vaguely mathematical passage in a work by Poe. Although I do not think it is mathematical enough to justify having its own entry on this website, it is interesting and so I will include it here for your interest:
Contributed by
Summer MacDermott
In Edgar Allan Poe's "A Descent into the MaelstrÃ¶m", the protagonist relates his experiences on a ship sinking into a powerful whirlpool. As the ship is descending down the whirlpool, the narrator recalls,
I made, also, three important observations. The first was, that as a general rule, the larger the bodies were, the more rapid their descent; the second, that, between two masses of equal extent, the one spherical, and the other of any other shape, the superiority in speed of descent was with the sphere; the third, that, between two masses of equal size, the one cylindrical, and the other of any other shape, the cylinder was absorbed the more slowly.
Since my escape, I have had several conversations on this subject with an old schoolmaster of the district; and it was from him that I learned the use of the words 'cylinder' and 'sphere.' He explained to me although I have forgotten the explanation how what I observed was, in fact, the natural consequence of the forms of the floating fragments and showed me how it happened that a cylinder, swimming in a vortex, offered more resistance to its suction, and was drawn in with greater difficulty than an equally bulky body, of any form whatever.*
*See Archimedes, "De Incidentibus in Fluido." lib.2.

The narrator proceeds to lash himself to a cylindrical water cask, and the whirlpool abates before swallowing him.
The starred note is Poe's and it is fake, as Archimedes did not study the mechanics of moving bodies in water. Nevertheless, the questions is still interesting: which geometric body will descend fastest into a fluid vortex? Georgios H. Vatistas attempted to answer the question here.

