If you don't find the answer from anyone on here, I would post the find on www.cwbullet.com. They specialize in all types of Civil War relics. Though, I'm not sure it the age of the bullets is the Civil War, they may be able to guide you in the right direction. Either way, nice finds! I would love to have those popping up in the front yard!
I don't profess to be a C.W. bullet expert, but I don't know of any that would have had a swaged channelure/lube groove. I'd guess post nitrocellulose powder era, 1890 to present, from a cartridge arm.
Nothing in the image to give a relative size comparison.