The guy I usually get my weights from (local owner of 5 tire stores- my payment to him is to cast and lube him about 500 bullets a year for loading his .38 special) just recently gave me a bucket.
In the past, I had found maybe 1-2 zinc ones per 5 gallon bucket. Easy to spot, so long as you watch your melt carefully and grab them with a spoon or tongs before they overheat and melt themselves.
Well in this bucket, just in the first 20 pounds that I melted down this last week, I found 10 zinc weights.
Sigh.
Course, I won't toss 'em. I have a downrigger mold that I can use them in.