This website may help you identify what kind of snake he is:
http://www.virginiaherpetologicalsoc...f_virginia.htm
Once you are sure of the species, you'll have a better idea of what to feed him and other care requirements. I'm not sure about pillbugs, but I know some snakes do eat earthworms. Others, like our BPs, will want something warm-blooded. So you do really need to do your research to keep him successfully.
Or just let him loose near the spot you found him before this little bit of a warm spell ends. Most likely his instincts weren't steering him wrong.