The Letters of William Godwin, General Editor Pamela Clemit, 6 vols. (Oxford: Oxford University Press, 2011–), is such an edition. It ‘publishes for the first time all the letters of this significant social thinker, novelist, and philosopher of the late eighteenth and early nineteenth centuries’.
For more information on this project and to keep up to date with regard to its progress see READ (Research in English at Durham).
The image below shows part of a letter by William Godwin (Bod. MS Abinger c. 9, fol. 34v). Pamela Clemit writes: ‘this letter is to James Wollstonecraft, one of Mary Wollstonecraft’s brothers, who was in the Navy, and is dated 3–5 September 1805. (He died on 19 September 1805 so it is not clear whether he received this letter.) The full annotated text will appear in volume II.‘
Further images of letters and other papers by Godwin can be found in the Bodleian Library’s Abinger Collection. It also contains correspondence of Mary Wollstonecraft, Mary Shelley, Percy Bysshe Shelley, and other letter writers.