Every time I walk past the bag bin at 7th and A St SE (see photo below), I see new bags in and old bags gone, so people are really using the bags. Try it out. Put a few of your Post bags and see what happens. My neighbor Dan just asked me for more Post bags, so you might ask a neighbor whether they want your bags.
On the cork front, I just got a huge bag of corks from Hayden's. Keep bringing your corks (natural and plastic) to Hayden's because the DC artist and the Missouri cork tile company need them. Also, if you can, try to use natural corks because World Wildlife Fund is asking us to support the natural cork industry in the Mediterranean -- it's good for workers, their economy, and the cork trees (see discussion in previous post). Power to the natural corks and the Mediterranean workers!