In an interesting case of recycling a biker friend who lost a wheel nut off his Harley was walking the bike down the side of the road when he found a large square galvanized steel nut that had fallen off a guard rail or been discarded by the installers. Figuring he had nothing to lose he tried it and was surprised to find out it fit. He was able to effect a temporary repair that allowed him to get to a garage.

I once found a knobby truck tire in a swamp. I would have tried to pull it out and properly dispose of it but I was on foot and in the middle of a thirty mile hike. The tire must have weighed several hundred pounds and it was buried in clay and sand. Just out of curiosity I cut off a few of the rubber chunks with my knife. Later I was lighting a fire and found the rubber made fairly good tender. It made the fire smoke and stink until the rubber was consumed but it worked pretty well.

Graduate school level training for surviving on what society throws away, people and materials, is found in the shadow society of homeless people. They aren't often pretty, or pleasant to stand downwind of, a lot have been through the wringer, but in a lot of ways they are survival experts.

If your careful, there are some you don't want to be near, and some are clearly mentally ill, you can get a little informal training by just offering a little respect and light conversation. When the weather turns cool bringing a coat you no longer need, a cheap sleeping bag that is worn out by your standards or a blanket can get you friend and a lot of inside information.

OT:
I wholeheartedly support any and all organizations and efforts to collect fishing line either by providing places to safely dispose of it and/or collecting it out of the environment. There are even organizations of divers, and a few commercial fishermen, who go out of their way to collect fishing lines, nets and rope from the water.

Ask around, look these organizations up and your likely to find a fine group of people. Consider contributing a few dollars and/or volunteering to help out. Most of the fishing line collection sites are assembled, installed, emptied and maintained by volunteers.