Do cucumbers grow above or under ground?

yes, unlike plants that require photosynthesys to make their food, mushrooms are decomposers and get their food from rotting vegitation.

Mushrooms can and do grow well in absolute darkness. However, they don't normally grow underneath the surface of the soil like a potato or carrot does. They still grow at the surface of the material upon which they are feeding, such as a rotting log, grass thatch, or crop residue left on the soil surface.