The mounds were and still are sacred places to American Indian tribes. Six mound sites spanning several centuries are protected by the Natchez Trace Parkway. Their contruction was a community effort. Emerald Mound at milepost 10.5, near Natchez, Mississippi, is the second largest American Indian mound site in the United States. When you visit the mounds, please remember these are sacred places.
There are hundreds of mounds in Mississippi, many of them are on the National Register of Historic Places. You can learn more about the here. Indian Mounds of Mississippi--A National Register of Historic Places Travel Itinerary (nps.gov)