What is the number one item that landfills are most populated with?

I used to do a lot of work on landfill sites as an electrician servicing the water pumps. When rain falls on the area the leechate has to be pumped off to avoid poisoning local water courses. Anyway, the fill sites were turned over once every thirty years or so and in some parts you could still read the newspaper print as it still hadn't broken down. There was a big problem with gulls flying all over the place, scavenging for food and sometimes getting caught up in machinery. The methane given off by the waste was sometimes pumped up from the ground and used to power electric generators and or detonated in a unit used to scare the birds off. Most likely thing to see in landfill would have to be the plastic bag... millions of 'em, usually stuffed with food packaging. Second would be plastic bottles, not sure of exact numbers or ratios but that made up most of what you could see. The sites were being dug up to retrieve metals from cans as the price of scrap metal went up to such an extent it became economically viable to do it. Fortunately recycling is becoming more popular these days and if people do their bit, can reduce the burden to find somewhere else to ditch it. These holes are pretty big ya know, and they fill up quick too.