I did a whole series of street trash for an Art is my Bag show many years ago. In addition to to photographs I collected the trash of the street and bagged it in clear poly trash bags with the location info for the exhibit. Had print and a slide show. It was great fun.
Sounds like a fascinating project. It was icing on the cake for you to include the bagged stuff in your show - location info, like an archaeologist. Somehow, street trash speaks to us, doesn't it?