These charming little green bells are usually invisible from human level; you have to get down to plant level and gently lift up the leaves, and there they are.
The leaves seem to provide an ideal lurking place for tiny spiders. The pictures above were taken in the Kane Woods Nature Area in Scott Township; the one below was taken in Fox Chapel.
For a description of the species, see the Polygonatum pubescens reference page. Note that there are two very similar species of Polygonatum in our area, treated by some botanists as indistinguishable; if any botanically inclined readers believe that these plants are P. biflora rather than P. pubescens, corrections are always welcome.