Stop in for a cup of coffee

My first thought is a trench and 8’ diameter precast reinforced concrete culvert pipes. Then seal and back fill with 18” of the pipe above grade. Add a roof, side lights and flat floor.
We are in lock step on the culvert idea! I was also looking at making it a root cellar/tornado shelter. Our property is in the tornado alley. Be a nice place to jump into in the event of a twisty! And a fan in the back strong enough to suck your hat off!