Here is all I know, based on my dad's expiriences. I also know a woman who's had 2 children and said she'd rather have 2 more than another kidney stone.
We live in the South by the way, and he's done construction for like, 30 years.
Iced Tea and calcium supposedly lead to it. He hasn't drank much tea, milk, or ice cream for the last 10 years and hasn't had anymore stones. Oddly, his would usually happen in the winter when he wasn't doing as much construction but would be doing something like running a chainsaw or bouncing around on a tractor and they would get shook loose.
Supposedly what happens is you have minerals in your kidneys, and in the event you get dehydrated, the balance of water is messed up in your kidneys as it goes to other vital functions, which means these minerals floating around are left in the kidney. They solidify or something and after a while form a stone (all this is just one theory). Of course it doesn't really matter if it happens once or twice, but if it happens often for months on end for years then the stones build up. Usually if you've been outside playing sports or working and at the end of the day your lips feel parched, its a good chance you're partially dehydrated.
Ancient Egyptians had them. They are more common in the American South-east than anywhere else in the world, so many doctors think it has something to do with the diet + weather.
The last time he had one, he sucked the fillings out of his teeth he was gasping in pain and clenching his teeth so bad.