I have used blade sharpeners with limited sucess. I use packing tape to tape them to the lid of a soup can, etc. then toss into my recycling. The tape is clear so anyone can see what they are picking up and they are smaller than the lid so the edges of the lid keep you from getting cut. I did this recently at our beach house because I couldn't figure out any other way to toss mine into the recycling without getting cut on it later when I sorted it upon my arrival back to home base with a bag full of recycling.
I love the "jar" idea - I use old pill bottles for my bent pins and needles and when it gets full, I seal it up and toss them into the garbage.