Train whistle in the distance.
Spring peepers.
Wood thrush---what a beautiful melodious song! I love to hear it on summer evenings.
Carolina wren outside my bedroom window, alternately calling things that sound like, "City bird! City bird", "Bird City! Bird City! Bird City!", "Teacher, teacher, teacher!".
Phoebes--they nest above my bsmt door every year. Their call tells me it's almost time for the babies.