The stones used to murder the lottery 'winner' has religious overtones, since many of the world religions have in their proverbial ecumenical closets the act of stoning. It's also a fully participatory activity, allowing and encouraging everyone to take part in the death of one of its members. Lastly, though it might be a bit of a stretch, the Lottery has been going on for centuries and no one really knows when it began, so the stones may also represent the 'stone age' or 'cavemen' mentality when stones were the weapons of choice.
