...Someeven using it in buildings & armor. Besides the farmers, there were other aspects of society that provided useful services. Some of the more foolhardy brave souls become miner-explorers, venturing deep into the trash. Some say that the most intrepid have touched actual earth, even. The exploits of these miners bring valuable history to the surface, as well as relics of considerable worth, from the time before. The rarest of these relics are anything weapon related(needless to say, not all of humanity went with the trash peacefully. More on mutated plants/animals later). Actual wepons were almost nonexistent due to degradation, but there are at least a few serviceable articles in existence. More important were plans for weaponry and sturdy materials(low-tier being fungus bark, high-tier being nokia & the like). Ventures such as these are usually funded & become the basis for small settlements. Such settlements have need of protection, so able-bodied persons took to living as mercenaries(the best of which were given nokia weapons).
The environment was not kind to man, but it was much less so toward the beasts & plantlife. Hazardous chemicals that were so often used in old industry have been strewn across the globe. They reaped horrible mutagenic effects on the living things, twisting away all but the hardiest & most ravenous plants, and altering the animals into horrible nightmare beasts.
(That's what I have so far, critique welcome, ideas as well)