Most of my early gas welding was with wire coat hangers. I'd pick them up by the box full for free at garage sales- people just wanted to get rid of them.
On a tip from an old Toolmaker, I tried something different.
I had cut down an old 1911 to a Detonics size pistol (before there was a Detonics size pistol) and needed to weld the lower part of the grip frame back on after removing a section above it.
This Toolmaker told me to go walk the city streets and pick up the lost spring tines from the rotary brushes from street sweepers. I was walking a lot anyway, so I went hunting and found maybe 10 in a month or so.
They were small, maybe .1 x .015 x 10-12" long, but they are absolutely the finest rod I've ever used for oxy acetylene welding. Smooth, easy to make great looking, strong welds. It worked well for this particular job, because the welds were small, & had to be strong & "pretty".
The old boy told me almost any spring steel works well, but coils springs are hard to weld with.
I still pick them up IF I see them, but my eyes aren't what they used to be.