Mushrooms, though classified as vegetables in the food world, are not technically plants. They belong to the fungi kingdom and although they are not vegetables, mushrooms provide so many important properties.
It is important to eat only organically grown mushrooms because they absorb and concentrate whatever they grow in. This trait is what gives mushrooms their potency, and able to detox heavy metals, as well as air and water pollutants, so healthy growing conditions is a critical factor.
http://thescienceofeating.com/2015/01/01/benefits-of-mushrooms/