I found this digging around in my grandparents backyard when their neighborhood was being constructed in northern Illinois.
![couldn't figure out how to add pictures
Looks like a chalcedony nodule, but too hard to tell from the photo. Can you please provide some more photos, including close-ups?
Sure, thank you for your response
Sure, thank you for your response !
Definitely looks like chalcedony. Is there more if it there or was it just this one piece? Do you have a piece of quartz handy that you can use for a scratch test?
It might be a limestone or something.... I don't know:)