Dumpsters in front of new construction are my favorite. Lots of good pine studs, OSB, and other stuff. I built a whole workbench (with a spot for table saw and storage) out of materials I pulled from dumpsters on the street when they were building a new subdivision behind me. Some of my favorite picks were unopened bundles of shingles (heavy!) that I will use for a shed some day, a bunch of brand-new pex tubing, and an entire case of caulk.