Visit these local resources for the Iowa City/Eastern Iowa area:
The Bur Oak Land Trust website (Iowa City, IA)
Visit these Conservation Burial Cemetery websites (US)
Close to Iowa:
Natural Path Sanctuary, (Verona, WI)
Casper Creek Natural Cemetery (Elizabeth, IL)
By State:
Prairie Creek Conservation Cemetery, (Gainesville, FL)
Heartwood Preserve, (New Port Richey, FL)
Bluestem: (Cedar Grove, NC)
Carolina Memorial Sanctuary: (Mills River, NC)
The Forest Conservation Burial Ground (Ashland, OR)
Ramsey Creek Preserve (Westminster, SC)
Larkspur Conservation, (Nashville, TN)
Duck Run (Penn Laird, VA)
Vermont Forest Cemetery, (Roxbury, VT)
White Eagle Memorial Preserve, (Goldendale, WA)
These are Hybrid Natural Burial Cemeteries in Eastern Iowa (not following Conservation Burial practices exclusively):
Oakland Cemetery (Iowa City, IA)
Cedar Memorial Cemetery (Cedar Rapids, IA)
Rochester Cemetery [Facebook link] (Tipton, IA)