Pete, don't want to answer for Ironman -- just to let you know what I've found here for iron -- it seems to be everywhere as scrap. Engine blocks, a piece of some kind of rail that I thought was steel turned out to be iron, some kinds of waste pipe, farm equipment, boilers, and steam radiators. And heaven forbid, precision machinery.
It's pretty easy to break up moderate and thin section cast iron with a sledge hammer -- one way of telling if something is iron instead of steel -- like the rail I found is that it breaks with a crumbly looking surface rather than bends or dents like steel.
I'm using radiator pieces because I'm a beginner and I thought they might be easier to start with. Because radiators were originally poured in extremely thin sections, I imagine it is easier to melt and will pour more fluidly and has enough carbon to remain gray iron without additions, than thicker section iron may. I may not be saying this properly -- ironman can correct!
Ironman, thank you for your wedge answers. I will try to do that, too, when I get to melting thicker iron. I do have ferro-silicon, but haven't used it yet.
I remember something about your using thin copper magnet wire sometimes to drop additions into the melt "on a string" so to speak.