The first number I found is an estimate of the number of homo sapiens that have ever walked the earth. 106,000,000,000. (http://www.scientificamerican.com/article.cfm?id=fact-or-fiction-living-outnumber-dead)
106,000,000,000 people. Ever. Ok. Ok?
The next number I figured I'd need is the average weight of those homo sapiens over time. After perusing a few sites and google books, I came up with roughly 173 pounds. So if we multilpy the two figures we find that if all of the 106,000,000,000 stood on a scale, they would weigh 18,338,000,000,000 pounds.
The problem is that I have found no way of estimating how much of that might still be around in a form that you could objectively say is part of a dead homo sapiens.
So we get guess-y.
If we assume that all of the organic bits are gone from most of the bodies, we are left with only the skeleton, which weighs 6 or 7% of one's total body weight. That comes out to about 11.25 pounds of the average body weight for homo sapiens. If all those bones are still around in some form, no matter how broken down they may be, to dust for instance, than that leaves us with 1,191,970,000,000.
We are left with One Trillion One-Hundred-Ninety-One Billion pounds of death.
Roughly.
These calculations began in my mind as a pile that somewhat resembles this one:
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Which is of a landfill in Mexico City which, according to the article it comes from, is very large and unmanaged.