I was photographing the moss, did not even notice the spider until I got home and uploaded the photos. Probably not enough of a view to ID it, but I can't resist trying; what little I can see does look fairly distinctive.
Am Peucedanum officinale
crab spider
BugGuide claims that the ventral markings differ between A. blanda and A. argentata. This one appears to perfectly match the BugGuide example of A. blanda which was collected and ID'd by epigynum: https://bugguide.net/node/view/1804174
Private property. Southborough, MA.