The twelfth stone is a block of granite, excess to the remodeling of the Lincoln Tomb at Springfield, Illinois. It is called the Culver Stone after the name of its donor, J.S. Culver, the contractor for the remodeling job, who had it carved as a memorial to Lincoln's mother, Nancy Hanks Lincoln. The Culver Stone was originally placed in front of the Nancy Hanks Lincoln headstone in the cemetery here. Dedicated October 1, 1902, the stone remained there until 1933 when it was moved to its present position to mark the end of the Trail of Twelve Stones.

The carving reads: Nancy Hanks Lincoln

The plaque reads: