I've been watching these in my backyard for about a week now. Usually I don't start to get Sclerodermas fruiting until late July. But hot weather in early June apparently brought these out a little early. The cluster is growing in grass, about midway between an English walnut in my neighbor's backyard, and an Eastern Red oak (Quercus palustra) in my backyard. Since I also have these fruiting under my house, I'm pretty sure these are mycorrhizal with the Eastern Red oak. I originally cultivated Sclerodermas back in 1985 in my backyard by putting mature sporocarps outside near an Italian spruce-pine. The spruce-pine is still there, but it getting much too large for the space it was intended to occupy, and so will be girdled in August of this year. I intend to do the same with the Eastern Red oak, and probably will inoculate the oak with eiher shiitake, Pleurotus ostreatus or maybe Hericium erinaceus after girdling it.