A childhood belief about monsters

When I was in Elementary School, my class sometimes had to run a mile in the form of going 5 laps around a field behind the school. When we'd finish, my friends and I would always sit away from everyone else and look into the forest that was right beside the field. One day we all saw a black thing in a tree. We were convinced this was a giant tree-monster that lived in the forest. We ran away but. still wanting peace and quiet, quickly found another spot. We saw another giant tree-monster there, so we started running across the tree-line, seeing them everywhere. There was no fence separating the forest and the field, so we were scared half to death. We came up with an idea. We made a "peace-offering" to the monsters made of plants and flowers from around everywhere. We figured they would eat that and be gone. We piled everything up and left promptly. The next day, it was gone. We thought we had saved the school. We didn't know at the time that they were just leaves and branches.