I was looking for my last name "Dees", which I have been told by my relatives has either Irish or English origins. My ancestors came to America from either of those two countries and apparently owned a tobacco farm somewhere in the Carolinas.
I was also trying to find the origin of my girlfriend's last name, which she has no idea about: "Woodside". Her name is Megan, which is English, but her parents did not choose it because they are English. Since you have said ethnic background is most important, I will not be surprised if you cannot find anything on this name.