Throwing Money Away

I just went through my trash for the second time in 2 weeks to find cash I'd literally thrown away. I got lucky this time and found the two twenties in my kitchen can. Last time around I had to root through a week's worth of trash out back before I came up with the missing twenty.
How does a person manage to throw out money, you ask? Easy, at least for someone who knows to look for her glasses in the freezer.
When I run errands I don't take a purse, just shove my card and I.D. in my pocket and go. If I get cash back, that goes in the other pocket with the receipt. And when I get home, cards go back into the purse, receipt goes in the trash.
Whoops.
I feel so bad for the guy who just got paid for a movie rental with a moist twenty I found under rotting spinach and last night's curry.