Cat, here are 2 links so you can see what's in your state. I have a couple of bird ID books for my area & sit & thumb through them form time to time. You'd be surprised how familiar you get with what birds you might see & then you see one in your yard & realize you know what it is!
http://www.indianaaudubon.org/...
http://indianajones.smugmug.co...
I have this one for my state of Florida. I love it! It is color coded on the edge of the pages so you look birds up by color. If you had this book when you saw the gnatcatcher, you would just go to the section for grey & then look at the birds whose main color is grey.
https://www.amazon.com/dp/1885061900/
You might find it cheaper on Ebay. Also, you might get ones for neighboring states as those birds can end up in your territory especially if you live near the border.