With spider prey. Alternatively to a Gnamptopelta obsidianator ID (http://bugguide.net/node/view/4734), it could be a spider wasp (Pompilidae family). BugGuide lists them as "likely mimics of such wasps as Entypus and Pepsis menechma."
Possibly on an old Scorias spongiosa patch underneath a beech blight aphid colony?
Specialist fungi -- fresh!