I found this berry growing in a wild blueberry/cranberry kind of bog area. At first I thought it was a strawberry when all I saw was the blossom. Now that the fruit has formed and ripened it looks more like a blackberry/raspberry. The plant is completely ground cover and has runners like strawberries. Berries are quite small. Any ideas?
Hard to be sure about the species from the photos, but looks like a black raspberry. Raspberry fruit forms a cap and when picked comes off the receptacle clean. Blackberry fruit has a central stem-like core and this comes off with the fruit when picked. Could be eastern trailing black raspberry, Rubus occidentalis, but there are a lot of Rubus species in Pennsylvania. http://plants.usda.gov/java/profile?symbol=RUBUS