Dirt

Once upon a time there was a sower who, when she was born, was given a plot to grow whatever she wanted on it. She was told that it was the best piece of earth with the most fertile soil in the world. She began planting cucumbers there, since cucumbers had been grown on that soil for generations and, sure enough, she grew the largest, juiciest cucumbers she had ever seen. Obviously this really WAS the best soil in the world.
That is, she thought so until she decided she wanted to grow something else. Bluberry bushes and pumpkins and strawberries. It seemed that no matter how hard she tried those fruits would never grow. She would see adjacent farmers harvesting everything, along with cucumbers, throughout the year.
She began to have serious doubts that her plot was actually the most fertile in the land. She was beginning to come home absolutley haggard from the effort it took to try to maintain the more difficult crops. She started to realize that, while her plot was perfect for cucumbers, it was practically fatal to all other kinds of fruits. People, who began to notice her worn out appearance everyday as she came up from the garden, told her that she must not be gardening correctly, or that she needed to stop gardening non-cucumber plants, since, if the most fertile soil in the world wouldn't grow them, perhaps they were just weeds.
It was too late though. She knew they weren't bad fruit. In fact, they were much more flavorful and nutritious and beneficial than cucumbers. She tried to grow a plot full of cucumbers again but it just seemed drained and empty around harvest time. Eventually she started buying soil from other plots and incorporating that into hers.
People disapproved, saying that she was ruining the best plot in the neighborhood. She just smiled and had another slice of blueberry pie.