Administered by:
Clover 
For centuries, it's been used as a domesticated ground cover plant. Clover nourishes other plants around it, by making trace minerals accessible and by fixing nitrogen from the air (it's a type of legume).
Just a few decades ago, it was considered an essential part of lawns. Clover seeds were always included with grass in seed mixes.
Then agricultural chemical companies convinced everyone it was a weed that needed to be killed, so they could sell both herbicides and lawn fertiliser.
