I found reference to a "Smallwood Plantation" in Missouri at this site: http://littledixie.net/Slave%20Housing.htm . The planatationwas in Jackson County.
The best source I've found for small hamlets, villages, and towns in Missouri that no longer exist is on http://thelibrary.org/lochist/ however trying to search on this site for Smallwood gave no towns, villages, hamlets.
I did find a reference to Smallwood (a man) who developed a town in Knox County. Check http://thelibrary.org/lochist/moser/knoxpl.html
Another good way to look for towns that have disappeared within Google Books. I found a reference to Smallwood's Switch which is "three miles south of Atoka". However, I believe Atoka is in OK
Book is After Removal: The Choctaw in Mississippi edited by Samuel J. Wells, Roseanna ??
Perhaps if you gave us the context of Smallwood Missouri we could be more helpful.