The unauthorized edition of 1856 is at Levy and American Memory:

Title: When I Saw Sweet Nellie Home. Song & Chorus.
Composer, Lyricist, Arranger: Words by Frances Kyle. Music by J. Fletcher.
J. Fletcher Publication: Portland: J.S. Paine, 1856.

When I saw sweet Nellie home / by J. Fletcher.
Portland, ME: J. S. Paine, 1856.

Other editions at American Memory:

When I saw sweet Nellie home. Gems of Southern song.
Macon; Savannah, Georgia, John W. Burke, [186-]

When I saw sweet Nellie home.
Macon; Savannah, Georgia, John C. Schreiner & Son, [186-]

When I saw sweet Nellie home / by J. Fletcher.
Boston: Ditson, Oliver, 1884.

The "ONLY CORRECT EDITION" Guest Q referred to is also reproduced in Richard Jackson's Popular Songs of Nineteenth-Century America (Dover, 1976, pp. 229-232). Jackson comments on differences between editions (pp. 284-285):

(1) The most famous line in the song is that which ends the verse and the chorus: "From Aunt Dinah's quilting party I was seeing Nelly home." It appears in the first edition (Paine). The first "official" edition (Pond), however, changes "Aunt Dinah's quilting party" to "an august evening party." Now, the substitution is not only inexplicable, the appearance of the word "august" is preposterous. Surely the word "August" was intended but was waylaid by one of the industry's typically careless typesetters. (If Fletcher was bent on improving the text, he missed the opportunity to dispense with the ghastly image o the "pink-eyed pimpernell" as well as the indelicate "path Where the cattle love to roam"; no farm boy in his right mind would walk his girl home at night on a route so adversely aromatic and hazardous to shoes.) In the "second" authorized edition issued after the renewal of the copyright (in 1882 by Fletcher and 1884 by Ditson), "Aunt Dinah" is mysteriously reinstated, the "august evening party" banished.
(2) In all editions examined (including one as late as 1908 by Century Music) the covers identify the song's heroine as Nellie; yet in the caption titles (just above the music) and throughout the text she is consistently referred to as Nelly.
(3) The 1856 pirated edition credits [Miss] Frances Kyle as author of the text. Fletcher's edition omits any author credit. The cover page of the 1884 edition credits [Mr.] Francis Kyle, while page one of the very same edition credits [Miss] Frances Kyle.

The version adopted in Lester S. Levy's Grace Notes in American History: Popular Sheet Music from 1820 ton 1900 (University of Oklahoma Press, 1967, pp. 99-101) is from the 1858(?) edition (Levy said this "was composed in 1858").