Mold-like substance in grass & around dogwood trees
Hi - The gray structures at the base of your tree are a type of wood decay fungus called dead man's fingers, Xylaria polymorpha. They are a sign that there is decay/dead wood at the base of your tree. Here is an article with information about this fungus.
If this tree is near your home, I recommend consulting with a certified arborist to evaluate the extent of the decay. The tree may need to be removed. You can find an arborist near you using this website from the International Society of Arboriculture, https://www.treesaregood.org/