@ Amphibious54- I am not sure where he found the bricks used for siding on the patio, but he said he found all of the sidewalk concrete over a six month period by driving around his neighborhood. When he saw sidewalk construction, he would stop and ask the workers what they were doing with the concrete.
They often said they were simply going to dispose of it, and were more than willing to give it to him and help him load it into his pick-up. He used old sidewalk from three or four different sidewalk construction sites in his area. He also said that old sidewalk concrete can be found at concrete recycling plants which can be found in most big cities. Good luck with your project.