For Foster's (nearly) complete collection of lyrics, go to these sites (2-4 are with MIDI):

(1) Center for American Music's Stephen Foster Pages
(2) Public Domain Music: The Music of Stephen Collins Foster
(3) Stephen Foster Collection / Sammlung 1826-1864 (McGrath's link)
(4) Stephen Collins Foster: American Dreams

The Lester S. Levy Collection of Sheet Music, a great site, has the 1850 edition of "AH! MAY THE RED ROSE LIVE ALWAY." Original sheet music of 40 songs, where of course "Ah! May the Red Rose" is, are reprinted in Stephen Foster Song Book, edited by Richard Jackson (Dover). Smithsonan's Critical Edition (2 vols.) is, I believe, out of print, but worth searching for.