Just got back from another trip to the demolition site.
I was able to get permission to dig more plants. Even though one entire block had been leveled, there were two trees and one wooden shed left standing near house #10 where I found these plants. I dug up more of these (whatever they are, possibly Ardisia japonica or similar) as I only had 2 or 3 from the first day. I'll try to get better photos when the rain stops.