There are a lot of Chipping Sparrows (Spizella passerina) that are guests at Tim's Diner. They are one of my favorites. They are normally ground feeders, as this one here is doing, but recently have discovered that if they land on the feeders they find there is a veritable buffet!
They are very small birds, as you can see here. Compare the size of the sparrow to the clover it's standing amongst and to the empty sunflower hulls next to it that have fallen from the feeder above.