• New information on Hays's life, family, and writings from 85 letters by Eliza Fenwick to Mary Hays composed between 1798 and 1828. These letters belong to the Fenwick Family Collection at the New York Historical Society. Though A. F. Wedd published the majority of these letters in The Fate of the Fenwicks in 1927 (Brooks also included portions of several letters from Wedd's volume in her edition of Hays's correspondence in 2004), Wedd's transcriptions were abridged, often faulty, and highly destructive to the legacy of Hays, for she omitted all references to Hays's extended family, a family with which Fenwick was thoroughly acquainted.

• Previously unknown and unidentified writings of her sister, Elizabeth (c. 1765-1825), a significant voice in her own right and whose novel, Fatal Errors, composed c. 1796-97, has only recently been discovered, establishing her as an important member of the Godwin-Wollstonecraft-Hays circle in the 1790s. 

• The discovery of Mary Hays's youngest sister, Marianna Hays (c. 1773-97), in whose home in Little John Street Mary Hays lived for part of 1796 and 1797, assisting her younger sister just after her marriage to Edward Palmer (c. 1771-1831) and what appears to have been a fatal pregnancy. Edward Palmer's brother, Nathaniel (1774-1840), married Joanna Dunkin, niece of Mary Hays, in 1798. The other brother of Edward and Nathaniel Palmer was Samuel Palmer (1775-1848), the father of the Romantic artist, Samuel Palmer (1805-81). All these connections of Hays to the Palmer family have not been previously known.

• The most extensive chronology of Hays's life, drawing on previously unknown material in Crabb Robinson's diary. 

• A detailed pictorial survey of nearly all the locations where Hays lived and an accounting of the locations of her immediate family as well as her numerous nieces and nephews taken from various Poor Rates books in the parishes in which they were living at that time. 

• The complete text of the "Memoir" of Hays that appeared in the Christian Reformer in 1844.

• A Biographical Index of more than 100 individuals who appear in the Hays Correspondence. 

• A complete bibliography of Hays's writings and those of her sister, Elizabeth.

• A substantial bibliography of critical writings on Hays.

• A complete accounting of all references to Hays in the diaries and correspondence of William Godwin and Mary Wollstonecraft.

• A complete accounting of all references to Hays in the diary and reminiscences of Henry Crabb Robinson.

• The wills of Mary Hays, John Hays (her father), and John Eccles.

• Several other pages related to Hays and her family of writers and other Dissenting women writers of her day.

An examination of the life of Mary Hays demonstrates the importance of expanding the parameters of our knowledge of the lives, family, and social networks of women writers during the Romantic Era. A salient part of that expansion is understanding the role genealogy plays in reconstituting the literary, familial, and social circles in which a writer moves and uncovering the ways in which the religious, political, and sociological forces within those circles give shape to a writer's life and legacy. Mary Hays was, from birth to death, a devout Dissenter, and her life can best be comprehended as a "Dissenting life," from her early years in Southwark and the small Particular Baptist chapel at the end of Gainsford Street to her final years in a boarding house in Clapton near her favorite niece, Sarah Dunkin Wedd, and her closest male friend, her fellow Unitarian Henry Crabb Robinson, who would serve as her final correspondent and a pallbearer at her funeral.