In "Everyday Use" and "Once Upon a Time," the authors use several methods to convey their themes to the reader.
In "Everyday Use," Alice Walker provides a stark contrast between two sisters growing up in the same household. Though they come from the same background, they have a completely different "take" on their heritage.
Dee outright dismisses the work her enslaved and/or repressed ancestors accomplished in America in order to provide a future for their families and their descendants. Maggie, on the other hand, embraces her heritage. By comparing the two, in their "struggle" over an old quilt, the reader is able to see where each character's priorities lie in life.
Even the title, "Everyday Use," presents the idea that for Maggie, heritage is something she embraces every day, which in essence honors the sacrifices of those who have come before her. For Dee, choosing an African name for herself and authentic African dress seem to be nothing more than the trappings she adopts because they "look good," which is the reason she wants the quilt: it will "look good" in her home.
The theme here, of course, is to know and value who you are, letting those elements define you as a person, and avoid defining yourself by things that have little meaning to you: they will have little meaning to others as well, which makes trying to impress others a futile act.
In "Once Upon a Time," Gordimer starts with the title to convey a sense of the unreal: that which is fantastic. The family members in the fairytale have all they could want to be happy, but they allow "what-ifs" to color their judgment. Though they are never threatened, they erect and install more and more sophisticated safeguards to protect them from the outside world.
With the story's title, the reader can sense one theme: that what we perceive should not be taken at face value. If we are not careful, we can be deceived by what we assume is true. It's important to remember also that the bad things in the story, like dragons and evil queens in fairytales, are the stuff fantasies are made of: one needs to be cautious about the world, but also vigilant to avoid becoming enslaved by fears that may not exist in that world.
A second theme is that we should be optimistic rather than fatalistic in life. The author uses the increasingly frightening threats from the outside world (conveyed to them by other people and the news, but only one time based upon their own observation) to drive their sense of safety and well-being from the minds of the family in the story so that they panic and move beyond common sense or reason.
Time that is spent in fear over unseen, unconfirmed threats, robs us of valuable opportunities to enjoy each day, thereby separating us from the beauties of the world as it truly is.