Through her mother, Eckley was a second cousin of Louisa May Alcott and a descendant of the early English colonist John May.

The women had a close and relationship, with Barrett Browning referring to Eckley as "sister" in several of her letters.

[5][3] The rift was reportedly caused by a disagreement over the truthfulness of Eckley's claims that she had communicated with the spirits of Barrett Browning's deceased family members.

[5] Much of the surviving correspondence, between Eckley and Barrett Browning can be found in the Berg Collection of the New York Public Library.

[2] Eckley's sketchbook, which contains sketches of landscapes in Nahant, Massachusetts, is held at the Clements Library at the University of Michigan.