You've checked all the links on this page? http://wiki.polycount.com/wiki/PBR Tons of swatches and values available. Rendering Remember Me for example.
I'm looking for a "definitive" reference guide for PBR - and by reference guide I'm pretty much asking for colour swatches or colour values for materials. Albedo + Roughness etc I'm finding a fair few "bits and bob's" over at quixel, marmoset and substance but each really only have a small example sample of material values…