What makes perfect circles in the ground?

Answer 1

you can take a thin stick or other cylindric object and jab it into the ground.

it has to be stiff. now take some string and tie one end around the stick so it would hang a little loose. on the other end attach another stick, but don't stick it in the ground. Now pull the string in one direction until its tight, but the stick not in the ground onto the ground and walk around in a circle, always keeping the string taught.