Two likely candidates for that part of the country are the cardinal, whose song consists of a series of strong farily shrill but at the same time quite musical whistles. Some are ascending in pitch and some are descending and others are a bit more warbling. Another prominant possibility would be the mockingbird which has its own song but, as the name implies, is capable of imitating many other species that are sympatric with it. Your local library may have recordings of bird songs that you could check out.

rich r