Sincerely?
Okay, cut out a circle. Cut the circle in half. Choose one point approximately a third from the top at the straight edge and fold the rounded part over to the other side crossing the chosen point (1.). Then fold the rounded part back to the other side (2.) and back to this side again (3.) using always a slightly larger angle:
At the end glue a rectangular piece of paper to the (backside) bottom to symbolize the trunk.