Foreshadowing gives us a clue as to what is to happen in a story, without actually giving away the plot. In the second paragraph of "The Lottery," we learn that one of the school children, Bobby Martin, has stuffed his pockets full of stones, as have some of the other schoolboys. The stones are an example of foreshadowing because they are a hint that the lottery everyone has gathered for is going to be more violent and bloodthirsty than we might normally expect. Another similar instance of foreshadowing in this second paragraph is the great pile of stones a group of boys makes in the corner of the square.
It is not so much that it is unimportant where the lottery box is kept as the shuffling around of the box indicates the community's growing discomfort with the lottery. It is an outmoded superstition, and while the villagers are unwilling to abandon the tradition, they also don't want to think about it. Shoving the box any which place is a way of being in denial most of the time about the barbaric custom they are maintaining, as is not repairing the box. Except for the day of the lottery, the townspeople want to disassociate themselves from what they are doing.