This small sac was suspended from the fern frond. It is more than likely the egg sac of a Ray Spider (Family: Theridiosomatidae, Genus: Theridiosoma, and probably Theridiosoma gemmosum). According to Bug Guide, there are only two species in North America. Despite looking and looking, I have not found another such egg sac (I wanted to try for a better photo). This was photographed in Larose Forest.