A hiker in Illinois discovered something unusual in a forest preserve, but the question is whether it poses a danger. Was A Cannonball Found In An Illinois Forest Preserve? You go to your local forest preserve to take a pleasant afternoon hike. While you're out on your adventure, you spot a very unusual item. The discovery of a possibly dangerous military cannonball in the Lake County Forest Preserves prompted a bomb squad response Sunday afternoon, according to the Highland Park Police Department.