Look for these outside villages, as many as 2 can be found out side any town/village. There is a chest in it and usually you can get weapons, guns or ammo. It's better allways get all the things, because you will need the ammo or weapons sooner or later.
The second building which the Day Z generator creats is a large stonebrick tower. It holds a chest at the top and contains stairs on the inside. They usually spawn in random locations but they are often found near villages.