What Berach do you make on a black truffle and on a white truffle and why?

Shalom, Thank you for your question. The correct bracha on eating truffles, both black on white, is shehakol. The reason for this is that even though the truffles grow on the ground, they do not grow from the nourishment of the soil (as do vegetables which have the brach ha'adamah), but rather they grow as a fungus (like all of the mushroom family). Because of this there blessing is not ha'adamah, that which grows from the ground, but shehakol. Blessings.