I noticed an unusual trilling call as soon as I stepped out of the car at this easement. Several males were calling in the open sandy area right at the end of the road, with scattered grass and leaf litter clumps. After wandering through the preserve, I returned to the car and made a targeted search of the area with singing crickets. I was rewarded with this female and an associated male, who both fit nicely with the description in Blatchley 1920 (=Nemobius griseus). The male's call also matched the recordings on SINA. The only other ground crickets present were Allonemobius tinnulus (and perhaps Eunemobius carolinus) - rather different in both appearance and song. Great to finally find this lovely species which I have been looking for in New England for quite some time. I have visited many other similarly open sandy places in the past, with no success.
It appears that these are the first photos of living individuals, as the only other depictions I can find are either drawings or photos of dead specimens. Odd that they haven't turned up on BG or iNat yet.