I just found a 3 gallon bucket of wheel weights by my garage door this morning when I got out. I have not tracked down the donor yet but the clue is the bucket! It appears to be a tire lube bucket which means I'll take a couple dozen donuts by the tire store in the morning! I'll sort them as soon as it warms up a little!
Last Summer there was a heaping full bucket of weights sitting in the same place. It took me longer to find that donor. It turns out that the parts store guy dropped them off. I went in looking for an "O" ring a few years ago and the guy recognized my Lyman 450 sizer for what it was and offered up a bucket of weights left over from when he shot Bullseye. This was a nice score, weights old enough to not have zinc or iron mixed in.
Like I have posted before, networking works! Maybe not immediately, but it works. Tell everyone you know that you need lead. Friends, Family, coworkers, any of them can surprise you.