Symbolism, Imagery, Allegory
It's The Circle of Life
If you think about it, quite a few scenes in O Pioneers! take place in the old pioneer graveyard. What gives?
Well, since we'll be talking about graveyards, it seems appropriate to start at the end of the novel. Let's take another look at that final line:
Fortunate country, that is one day to receive hearts like Alexandra's into its bosom, to give them out again in the yellow wheat, in the rustling corn, in the shining eyes of youth! (5.3.31)
That sounds nice, but what's really being described here?
Think about it: the narrator is looking forward to a time when Alexandra will be "received" by the country, and given out again "in the yellow wheat, in the rustling corn," etc. Though it might sound morbid, there's no two ways about it: these lines are describing her death and burial.
The reason this passage doesn't mention that whole dying part, is that it chooses to see Alexandra as part of a life cycle. She is born, lives for a while, and is then "received" again by the land, to be "given out" again in new forms of life. In this view, death is not an end, but simply a continuation of life.
Haven't We Heard This One Before?
The image of the graveyard serves both to remind the reader of the inevitable reality of death, while also emphasizing the life cycle of history. Check out the conversation between Carl and Alexandra, which does just that:
"Yes, sometimes, when I think about father and mother and those who are gone; so many of our old neighbors." Alexandra paused and looked up thoughtfully at the stars. "We can remember the graveyard when it was wild prairie, Carl, and now—"
"And now the old story had begun to write itself over there," said Carl softly. "Isn't it queer: there are only two or three human stories, and they go on repeating themselves as fiercely as if they had never happened before; like the larks in this country, they have been singing the same five notes over for thousands of years." (2.4.13)
Here, Alexandra starts the conversation by thinking about her deceased family members and neighbors. Life has changed for her and Carl, and the graveyard keeps a record of that change. Then Carl, thinking of the budding romance between Emil and Marie, muses that human lives just repeat the same themes, over and over. Even when death ends one life (or two lives), the "human stories" will continue in the next generation, just like the seasons repeat themselves every year.
Let's recall some other scenes when the graveyard figures obviously. For example, the second time we see Emil and Marie together, as full-grown adults, Emil's mowing the grass on the graveyard (Part 2, Chapter 1). And much later, after Emil and Marie are murdered, Ivar and Signa find Alexandra next to her father's grave. She stands up to meet them, seeming to resurrect her father, but also to rise up from under his influence:
When Ivar stopped at the gate and swung out his lantern, a white figure rose from beside John Bergson's white stone. (5.1.17)
And then, Alexandra talks about the dead with Ivar:
"Maybe it's like that with the dead. If they feel anything at all, it's the old things, before they were born, that comfort people like the feeling of their own bed does when they are little." (5.1.24-26)
We can tell here that Alexandra doesn't believe, like Ivar does, that the dead continue life in Paradise or Hell. Instead, she imagines the dead returning to a previous state. She likes to think that the experience of death is something like the way things are "before they were born." Here's another example of death symbolizing a return to the beginning, rebooting the whole system of life.
Life is for the Living—Or is it?
In O Pioneers!, the graveyard sets the stage for discussions of death and "human stories," in which death is envisioned as part of life, not its end. Life goes on, the stories return, but each time, as Alexandra comes to see it, the stories have different authors to write them:
"You remember what you once said about the graveyard, and the old story writing itself over? Only it is we who write it, with the best we have." (5.3.23)