Wumps are cute little gopher-like creatures featured in a children's book by Bill Peet. They eat grass under the bumbershoot trees, and lead a peaceful happy life, like the Barbaloots in The Lorax.
Alas, one day some scary aliens in spaceships, the Pollutians, land on the Wump planet and cover it with factories and ugly highways that pollute the land and make the grass die. The forlorn Wumps hide underground to eat mushrooms in miserable caves. After the Pollutians have wrecked the whole planet, they leave to find a new world, and the Wumps come out of hiding to find one last hidden meadow where they can begin to rebuild their pastoral Utopia.
This book is guaranteed to make your kids think that littering is a capital crime.
"In time the murky skies would clear up and the rains would wash the scum from the rivers and lakes. The tall buildings would come tumbling down and the freeways would crumble away. And in time the green growth would wind its way up through the rubble. But the Wump World would never be quite the same."