They seem to select sandy loam that contains root exudate they like. They don't bother to fruit unless there favored conditions are interrupted. They seem to favor roots of pomoideae, Apples, pears and other pome fruit. I had a huge crop one year when I covered a sandy orchard soil with cardboard and maple leaves. but the fruiting bodies were in a line where the cardboard ended and interrupting the growth of the mycelium. I found a surprise fruit yesterday in one of my wicking barrel planters that was under an apple tree and I pulled the roots out from the plant that did not survive the winter and then it ran low on water..