Foreshadowing is a signficant element in "A Rose for Emily", used in several places in the story.
Foreshadowing is used to set up the story as it opens. The fact of Emily's death is presented before the history of her life, effectively creating a degree of anticipation in the reader. This initial use of foreshadowing becomes part of the structure of the story.
Later, the death of Homer Baron is foreshadowed.
The narrator foreshadows the grisly discovery at the end of the story with several scenes.
Emily's purchase of rat poison along with the many details of her secrecy help to subtly foreshadow Baron's death (and, likely, murder), as do the details relating to Emily's reaction to her father's death and the stink that emanates from her house for some time.