The natural color of the moss, combined with some creepy-crawly embellishments, will make it appear as though you pulled the wreath from the depths of a cobweb-covered attic.
Hot-glue handfuls of moss to a Styrofoam wreath form until covered.
Apply a thin coat of craft glue to plastic spiders (available at Halloween stores); sprinkle with black glitter. Hot-glue spiders onto wreath.
Hang wreath using monofilament.