I wasn't at all sure what kind of bird it might be. I thought it was likely a Pine Warbler or possibly a Common Yellowthroat. We had not seen any adult Pine Warblers recently, but we had seen adult yellowthroats. I sent the photographs to a local bird expert.
Imagine my surprise when she told me it was a juvenile Blue-Winged Warbler! A lifer for me, and I had no idea. There are no records of breeding pairs in our county, so it seems this little guy might have wandered over a neighboring county where they are rare, but nesting pairs have been documented.
I won't even complain that it was such a cloudy day and the pictures would have been so much better with in the sunshine.
I was content to have gotten the photograph and glad that I was skeptical enough to seek an expert's opinion. My thanks to all of you who are experts and willing to share your knowledge. Oh, I can't wait for the fall migration!