One example of a metahpor in the story can be found in the narrator's perception of the woman, or women, trapped behind it. The wallpaper metaphorically represents the narrator's entrapment in a world of domesticity, a world of oppression in which she is not happy. The metaphor might easy apply to other women that the narrator concedes may be in the same position.
“Sometimes I think there are a great many women behind, and sometimes only one...”
The Yellow Wallpaper