Far too much to the discerning eye.
It tells of what you eat, what you read (magazines and offers), which charities you donate to, which you toss unopened and thus gives insight into your political beliefs. It tells what drugs, including caffeine, alcohol, and tobacco you consume and how often/much, and sooner or later, what prescription drugs you take as well, which could give insight into your health and any chronic maladies you may suffer from. There is a lot more that can be discerned by studying trash, but that's a good start.
