I lead a group of students in a community service project where we refurbish or repair donated used bicycles. When we have a bike in safe acceptable condition, we donate it to the local children's shelter and other county support agencies.
I am always searching the recycling center, dump, garbage areas, anything, anywhere a rusty old bike may be. I'm not above stopping at someones house and asking them if they would like to give me that old bike out in the yard.
It's amazing the parts that can be salvaged from even a rusty old bike that appears useless. It's also amazing how many people buy bikes and then just leave them in a barn (etc.) and don't ride them for five years.
We buy tires, chains, cables, brake pads, etc. but mostly we recycle parts from one bike to another. We have already donated about 50 bicycles and probably will donate another 20 or so by May.
Your bike trash is someone elses bike treasure.