Trash rocks can be used as benches, tables, sculpture bases, landscape accents, and walls. A family living in one location over time could build a castle out of their trash. I would expect trash rocks to have good thermal insulation, useful in both hot and cold climates.
I'm big into recycling and built my whole house out of recycled nylon fishnet and cement, a material I call nylon-cement. For many years I eliminated all my trash right at home using trash rocks.
Ideally, I would like to see a chemist develop a way to recycle some of our plastic trash and make a mesh material like fishnet out of it that could be plastered with cement.
Recycling is all about mining trash; converting waste into something useful. If we separate our trash first and put it into separate trash rocks we would know where to look for specific recyclable materials in the future when we need them. In the meantime, why not enjoy living around all the trash we generate?