The stones that the villagers use to kill the victim selected by the lottery are mentioned periodically throughout the story. This repetition develops the stones as a symbol violence. The villagers use these to kill Tessie.
Verbal irony occurs with this comment by Mr. Summers, who is in charge of the lottery's proceedings: "Thought we were going to have to get on without you, Tessie." As it turns out, they cannot "get on" without Tessie, because it is her name that will be drawn. The entire lottery hinges on Tessie Hutchinson this year.
During the initial lottery, as the household heads draw slips, each family unit is pitted against all the others. The bonds between families remain, but the overarching community bond dissolves. This dissolution of community bonds is exemplified when Tessie calls for a redo of the initial lottery. She is willing to sacrifice another family as long as it means that her family is safe. After the first round of the lottery is over, the families who were not chosen can re-assimilate into the community. The main theme of the lottery is safety coming from being in a group.