Need a little more information, they look like rock to me, did you find them with a detector? If both assumptions are true I’d guess they are stones with a concentration of iron in them
Unfortunately I don’t see any evidence of altering by man. Look for flint, quartz, obsidian and such. Then look for flake scars and a wavy edge for worked pieces. It takes repetition and a bit of learning and it will become easy to identify most artifacts