I came up empty, so today I decided to explore a different area. The dreaded 'east side'.
Almost immediately there was a Mourning Warbler singing its heart out. It was well hidden so didn't offer a good photo opportunity. But about an hour later we found another Mourning Warbler singing right out in the open:
Savannah Sparrows were singing in a nearby field:

I'm off to the Carden today, maybe a Henslow's Sparrow will be singing there?