Certainty about their ID is difficult, without additional photos (and info) ...but for the moment, they appear to be fired shotgun-slugs. If so, they ae a 20th-century version of shotgun-slug, definitely not civil war era.
Do they all have the same hole in the base?
In particular, a side-view photo is needed, of the one at top left in your "group" photo of them. But not too close, please, because the closeup photos you posted look very blurry on my computer-screen.
You were right to put quotation-marks around the word "lead" in your description of them. They appear to be made of a "hardened-lead alloy" ...not pure lead. By the way, that alloy is typical for 20th-century bullets. Most (but not all) ciil war bullets were made of 100% lead.