Clearly, mine looks like yours - except for the antenna tips which, in my case are yellow. Two printed field guides tell me that a Field Crescent will not have yellow anntenna tips. Different subspecies? Time to re-write the book?

I didn't notice the color of the antenna tips, so I don't know what to make of it. Interesting, though.

You were correct! According to Dr. Arthur Shapiro at UC Davis:

"It's an old female P. campestris (Field Crescent). The antennal club is
half brown (basal) and half yellow (distal). The median band is often
paler than the rest of the ground color, and on old specimens may fade to almost white (as here). Note that much of the hair has worn off the back of the thorax, another indicator of aging; I'd guess she was 2-3 weeks old. There is nothing at all unusual about her in the context of long series of the bug! Half the trick in a field guide is convincing readers that a certain amount of variation is to be expected."