Mary, I'm interested, as I have been collecting Foster books. "Myths" listed (Click here) at Stephen Foster Pages (Center for American Music, University of Pittsburgh) are:

Foster was a Southerner
Foster wrote about the "Swanee" River and the old Kentucky home after (or while) visiting those sites
Foster was an idle dreamer, an untrained musical genius whose songs were flashes of inspiration
Foster was incapable of any kind of work, and did not have to labor at writing music
Foster got many of his musical ideas by listening to slaves or attending black church services and then simply writing down what he heard
Foster was a racist who glorified slavery and the happy life for slaves on the plantation, and who regretted the abolition of slavery
Foster earned a great deal of money but was financially inept
Foster was a carefree, spendthrift artist who neither knew nor cared about money
Foster hated school, and was therefore poorly educated
Foster was gay
Foster committed suicide
Foster was a drunkard who died intoxicated in a Bowery gutter

~Masato