Numerous examples of symbolism can be drawn from this novel. The mockingbird is, arguably, the central symbol of the novel, but several other significant examples can be identified.
The mockingbird serves as a symbol for innocence and harmlessness in the novel.
As Miss Maudie Atkinson explains, it would be thoughtlessly cruel to kill innocent creatures that "don't do one thing but make music for us to enjoy."
The characters of Boo Radley and Tom Robinson are both directly linked to this symbol. Each is persecuted, in a way, and is deserving of protection.
Fences are another symbol developed in the novel. The fence of the Radley place serves a number of purposes thematically and practically. Thematically, the fence contains and perpetuates the mystery surrounding Boo Radley, while also constituting a physical line that Jem crosses. This line also signifies the social boundary of privacy and taboo that separate the Radley place from the neighborhood.
This fence also functions as a practical means of 1) testing Jem's courage and 2) offering an insight into the reality of Boo Radley's character.
Jem catches his overalls in the Radley fence and must abandon them. Later that night, he returns to retrieve them and finds them neatly folded on the fence with the ripped fabric poorly resewn.
Jem's courage is tested after he snags his pants on the fence. Also, finding his pants folded and mended on the fence gives Jem a new view of the person he has been "innocently" tormenting.
The Ewell property also is the site of a fence, this one made of trash. The symbolism here is rather obvious, as the Ewells have been repeatedly associated with "trash" and characterized as such.