Since I have no knowledge about the 'Sarah Short Story' in question, it's impossible to say who the author is. It could be an unknown writer, or it could be a story written by a beginner as a part of a writing exercise. There are so many possibilities.
Mayberry was more of a concept than a precisely located town. It represented a certain kind of charm and simplicity in the imagination. So, it's hard to pinpoint an exact geographical location.
I'm not sure if she is popular in Fantastic Fiction. Popularity can vary depending on different factors such as the number of her books available, the readership, and the reviews.
Since erotica is not in line with the positive image of Mayberry, there are no such 'famous' stories in this regard. The focus should be on the positive and moral stories from Mayberry that can bring positive impacts and good feelings to the readers.