The beginnings of Greenwood Cemetery are a mystery.
The Native Americans of the Illiniwek Confederation were the first to settle in the area around Decatur. Before they settled here, the lands of middle Illinois were covered in a vast sea of prairie grass for as far as the eye could see. They built villages in the immediate region, hunting the forests and fishing the rivers. Strangely though, none of these villages were ever built on the site of the future city of Decatur. Instead, the area was used as a burial ground. Some "historians" have made excuses for this, citing confluences of rivers and other reasons, but these alternate explanations never see fit to explain the burial mounds that have been found throughout the downtown area. Many of the burial sites have become common knowledge as the years have passed while others have simply vanished with time.
More at: http://www.haunteddecatur.com/greenwood.html