OK. Weird thought... If you went to a landfill, what would be the most common solid waste you saw? A number of years back, a greeny asked that question and challenged people to go see for ourselves. It's been bugging me ever since. Here are some quick Googled results.
The most common waste product is paper (about 40 percent of the total). Other common components are: yard waste (green waste), plastics, metals, wood, glass and food waste. The composition of the municipal wastes can vary from region to region and from season to season. (U of Cal)
Paper, Organics (in Canada, from an Amazon "search inside" book)
Malaysia: Plastic waste is the most common solid waste that we generate in the country accounting for 7-12 percent by weight and 18-30 percent by volume of the total residential waste generated.
Throwaways (diapers) comprise 2 percent of the nation's solid waste by weight, making them the third most common solid waste item after newspapers and beverage and food containers. (diaper "activist" site, NY)
So "paper" is #1 and is quite recyclable, and energy rich. Plastic and organics too (possibly #2 and #3, if you include diapers; heh!).
Still doesn't answer what the "source" of the paper and plastic is. Fast food bags and wrappers? Retail boxes/packaging, grocery packaging, industrial/wholesale packaging? Books, junk mail, printouts?
I'd love to have a reference to a more detailed discussion of the source data. Not the reinterpreted-for-an-agenda summaries. And then make my own conclusions about reducing. (Maybe I should just look in *my* trash can at the end of the week).