My two nemesis sparrows are Field sparrow and Clay-coloured sparrow. I've seen the former a few times but never managed a good photograph. I've yet to encounter a Clay-coloured sparrow, or (until yesterday) a Grasshopper sparrow, among others bordering on rare. One of the first sparrows I ever photographed was the Savannah sparrow (using a point-and-shoot camera) but the habitat that those sparrows were working has since been eradicated by progress. Since that time I've only seen a Savannah maybe once, or twice. Yesterday I finally got a DSLR-quality picture, albeit a Dx sensor version of this sparrow, as well as a Grasshopper sparrow.

Savannah sparrow ... note yellow lore

Grasshopper sparrow

Grasshopper sparrow ... note rusty to orange lore