The story opens with Mrs. Freeman, Mrs. Hopewell's hired help, wearing a "neutral" expression. She won't reveal herself to others. We learn, too, that Mrs. Hopewell is condescending to Mrs. Freeman, saying she is not "ashamed" to introduce her to friends. She also refers to the Freemans not as "trash," but as "good country people." We also learn that she hired them because she had no other choices.
Mrs. Freeman frames the story because she has more insight into human nature than either Mrs. Hopewell or Hulga. In a sense, she stands outside them, framing them, because she can understand more than they can. As the opening shows, she knows enough to be guarded around other people. Since she and Manley are designated "good country people," we can imagine that she has depths that Mrs. Hopewell can't perceive.
At the end, we get an insight into Mrs. Freeman's mind and realize that she is truly is more perceptive than her employer. The evil smelling onion she is unearthing possibly makes her think that Manley might be evil too. She has the wisdom to realize there is more to him than meets the eye, as the end of the story shows:
Mrs. Freeman’s gaze drove forward and just touched him before he disappeared under the hill. Then she returned her attention to the evil-smelling onion shoot she was lifting from the ground. “Some can’t be that simple,” she said. “I know I never could.”
Mrs. Freeman is freer than Hulga and Mrs. Hopewell because she doesn't feel superior to people and is able to understand that people are more complex than they might seem.
Bookending her story "Good Country People" with Mrs. Freeman allows author Flannery O'Connor to reinforce the irony of the story, a key technique she uses to communicate her themes. At the beginning of the story, readers meet Mrs. Freeman, Mrs. Hopewell's hired hand, and learn about her three expressions: neutral, forward, and reverse. Mrs. Freeman has strong opinions about nearly everything and rarely reverses them. Despite her employee's quirks, Mrs. Hopewell is confident that Mrs. Freeman's family are "good country people."
Similarly, Mrs. Hopewell believes Manley Pointer, the Bible salesman, to be "good country people." That is not the only thing Mrs. Freeman and Manley Pointer have in common. As it turns out, both of them share a fascination with Hulga/Joy's wooden leg. Mrs. Freeman never tires of hearing about the hunting accident that resulted in the amputation of Joy's leg, and Manley Pointer ends up seducing Hulga for the express purpose of purloining her prosthesis.
In the final paragraph of the story, as Mrs. Freeman unearths an "evil-smelling onion shoot," she remarks in reference to the fleeing Manley Pointer that "some can't be that simple. ... I know I never could." There are many layers of irony captured in this ending, just as the onion Mrs. Freeman holds has many layers. One is that Mrs. Freeman's morbid curiosity is ill-mannered and hurtful--maybe not to the degree Manley Pointer's was, but it bore a similar pungency. Another is that Mrs. Freeman's lack of insight into others is matched only by her lack of insight into herself. And another is that good country people cannot necessarily be taken at face value--one never knows what is under the surface until one has the chance to unearth the bitter fruit. As usual, Flannery O'Connor chooses her story's elements with great skill to convey a caustic view of the human condition.