Harry Dichter & Elliott Shapiro, Handbook of Early American Sheet Music 1768-1889 (1941; reprinted Dover, 1977, p. 92) says that the sheet music announced as "one of the latest songs" (linked to above: Date: 24 Jan 03 - 10:00 AM) is the third edition. This edition is also at HERE (UNC-Chapel Hill Music Library).
According to Calvin Elliker, Stephen Collins Foster: A Guide to Reseach (Garland, 1988, p. 66), Frédéric Louis Ritter's Music in America (1890) concludes with "the oft-repeated myth that Beautiful Dreamer was Foster's last composition." The myth continues even now. See, for example, Songwriters Hall of Fame: Stephen Foster, which says: "His death followed the completion of his last great song 'Beautiful Dreamer'. Written two weeks earlier, Foster wrote in his trademark sentiment about escape from bitter realities."