You may find Field Sparrows around here. It is a common sparrow of brushy pastures and old fields. It has an unstreaked chest, a gray face, and a pink bill. It has a simple, yet distinctive song of repeated clear whistled notes on one pitch that increase in rate until they make a trill. Think of a ping pong ball dropped on a table: the sound starts slow and gets faster. Hopefully this will be a fast park and grab for you. Update 5/20/14: Since the cache disappeared, I replaced it in a similar, but different place about 45 feet northeast.