The best (and funniest) example of foreshadowing is when Minny shows up at Hilly's house with a chocolate pie. Because Hilly is so pretentious—and because Minny is a strong character with a good dose of sass—the reader has a feeling that this isn't just a peace offering. Seemingly oblivious to the idea that anyone would dare challenge her, Hilly eats two slices, unaware of what the pie really contains: human excrement. This foreshadows bad things to come for Minny as the reader is certain of Hilly's racism and vindictive nature.
Sure enough, when Hilly discovers the truth, she sets out to destroy Minny in every way. But the reader becomes aware of a further truth: it would mortify Hilly if anyone ever discovered what had happened. This foreshadows another truth: Minny actually has the upper hand here and will use it to level the playing field in this secretive game. (The women include this story in their book as a means of keeping Hilly quiet and keeping themselves safe in their town full of racism and violence.)
A second piece of foreshadowing is a piece of advice Skeeter is given from Elaine Stein: "Write about what disturbs you, particularly if it bothers no one else." Skeeter really ponders this advice and begins to consider her close relationship with Constantine. This piece of advice foreshadows the book that Skeeter will eventually write about the injustices that the black maids suffered in her town.
Constantine herself provides some foreshadowing in a conversation with Skeeter, who reflects:
Even though I felt miserable, and knew that I was most likely ugly, it was the first time she had ever talked to me like I was something besides my mother's white child. All my life I'd been told what to believe about politics, coloreds, being a girl. But with Constantine's thumb pressed in my hand, I realized I actually had a choice what I could believe.
This foreshadows Skeeter's break with her community's values and even the values of her family. The reader is aware that Skeeter is going to make her own way—valuing people over prejudices.