I have no idea what kind of mushrooms these are, but they are really big!
Okay, after I wrote that, I googled giant white mushroom maryland and came up with a couple of possibilities: Clitocybe gibba or Clitocybe maxima. The first one seems correct but not big enough; the big one isn’t supposed to be found this far east. But this is my best guess.
My husband took the first photo. All photos were taken with his brand-new Nikon Coolpix S3500, which we got for him to take to Greece next week.