The accepted theory is that Poe may have become inspired to write the story "The Fall of the House of Usher" by events that took place years before he was born, in the year 1800. According to the Guide to Boston (AIA, Susan and Michael Southworth p. 59), there once was an "Usher House" that stood in Boston's Lewis Wharf. At least, it is true that a house was registered to an "Usher," who lived there with his young wife.
The legend goes that, years after the owners had passed, the house remained derelict and had to be demolished like other properties in the area. The grisly discovery of two human skeletons beneath the remains, holding one another in an embrace, propelled a number of potential theories as to what went on in the house.
The legend goes that the young wife of Usher was having an affair with a sailor, and that the two would meet at the Usher home, where they would hide in the cellar area. Apparently, Mr. Usher found them in action and locked them in the cellar, presumably until their deaths.
The news must have circulated around town for years, as Poe was not born until 1809 (this was right around 1800). The fact that we still hear the story more than two centuries later means it quickly reached urban legend status, a folklore, so to speak, where details are added year after year. It is no surprise that Poe may have grown up hearing the story of these two locked up lovers who were basically prematurely buried in a cellar. The idea of a locked cellar with live people inside squirming for their lives for days on end may have also prompted the writing of "The Cask of Amontillado" and "Premature Burial," where the characters suffer the horror of being put in a sealed space with no control of their circumstances, left to die.