I really enjoy the scene at Calpurnia's church, but it may take more background work than some other scenes to turn it into a short story. It seems to me the storyline with Mrs.Dubose would be a great one to re-create into a short story form. It has a clear beginning (Mrs. DuBose taunting the children in her forbidding manner), middle (Jem paying the price for having let his temper get the best of him), and end (the news that she has died a "free" woman). There is an important theme regarding both Mrs. DuBose and Jem, as well. Good question!
The previous post by clairewait gives some excellent examples of scenes from To Kill a Mockingbird that could be rewritten as short stories. However, she failed to mention one of my favorite chapters--and the first one that comes to mind that could be perfectly adapted in short story form: the tale of the rabid dog (Chapter 10). This chapter could easily be read separately from the novel without a great deal of exposition. The chapter tells a complete story, reveals new information about Atticus' background and secret skills, and teaches solid moral lessons about killing and parental respect.
I think because of the way To Kill a Mockingbird is told from Scout's adult perspective on her childhood, certainly many of the memories from the novel could be taken out and re-written as short stories. Consider how many stories-within-the-story there are. While the trial scene was rather long and built up to, even if isolated as one day in Scout's life, it would probably make perfect sense as a story all by itself. Other scenes which could easily be isolated into their own short stories include:
- Scout's first day of school.
- The ghost stories of Boo Radley.
- The night Jem loses his pants.
- Reading to Mrs. Dubose.
- Visiting Calpurnia's church.
- The Missionary Tea.
- The pageant.
The difference, of course, in isolating these scenes, is going to be a different perspective on the lessons learned. When looked at independently, the humor could still shine through, but the life-lessons would certainly be more focused on Scout's growing up, rather than the prejudice/racial element that is so subtly pervasive throughout the novel.