One type of mushrooms form symbiotic relationships with plants that photosynthesize. This relationship is to their mutual advantage. This is a very difficult type of mushroom to cultivate, although truffles are being grown on hazelnuts and oak trees in Europe on high-calcium soils.
The second type of mushroom is more antagonistic. They attack living plant. They enter through wounds and rot out the plants (trees) from the inside.
The third type of mushrooms are the janitors of the forest and pasture. They break down dead plant tissues. These have been the easiest species to domesticate.
Fungi will very happily grow without throwing up fruiting organs (mushrooms) as long as there appears to be "headroom", that is, room to keep expanding. An assortment of triggers fire as the mass of fungi have fully exploited the resources of the log or mass of vegetation. Those triggers cause the mass of fungi to shift from expansion to reproduction mode....they start making mushrooms.
In many, many cases the choicest species of mushrooms for edibility eat wood or grow on the roots of trees.
So, anybody with a brain will look for trees. Not just any trees, but old trees. Trees that are senile and sending out all of those triggers that coax their mushrooms...both the destroyers and the symbiots, into fruiting.
Here is the map of standing woody biomass courtesy of Woods Hole Research Center.
|Link to Image with zoom capability|
|Maple River running East-to-West across center of image. Picture courtesy of Google Maps|
Closer to Eaton Rapids, the Maple River valley looks very promising. It is also notable that many "sections" have mature woods in their centers, even in hard-core ag areas like northern Clinton County. I am going to have to buy a plat book and start contacting land owners.