With regard to Harper Lee's To Kill a Mockingbird, when you refer to "stationary objects," I expect you are referring to elements/essential parts of the story, regarding the literary "landscape," that are unchanging, in Chapters 1-8.
The first object would be the Radley house. It does not change, and neither does the activity outside of the house, with regard to its inhabitants. When Mr. Radley dies, the Jem and Scout expect Boo will finally come out, but his brother Nathan arrives and nothing changes.
In terms of what remains unchanged, perhaps I could suggest the community, and its long-standing members such as the Cunninghams, the Ewells, the Radleys (especially Boo), as well as Dill, Miss Stephanie and Miss Maudie.
Another stationary item in the story would be the oak tree on the Radley property in which Boo leaves "presents" for Jem and Scout, in an attempt to make a connection with them—and the outside world. Later the knot hole in the tree is cemented up when Mr. Radley attempts, once again, to close off Boo from the rest of the world.
An additional constant that appears several times in Chapters 1-8 is the school. Here learning takes place, or does not. Scout navigates new waters socially, both with her teacher and fellow students in the play yard. It is a source of irony, and a keyhole through which the reader can look to discover the underpinnings (undercurrents/inner-workings) of this town.
Throughout the story, there are certain constant elements that run into view and out again, appearing in one chapter and later in another or several others. These are essential to creating the setting and "landscape" of the plot and the characters.