Re English walnut (juglans regia) this really originally comes from Persia. I used to live in Persia and can recall getting very black from the sticky walnut husks when attempting to gather same to eat. I have done the reverse in my own woodlot planting black walnut (juglans nigra) in the hope that this will provide a valuable harvest of timber in 100 years time. I have found that it is not easy to extract the mature nuts from black walnut and this is quite the opposite from the relative ease with which an English walnut can be cracked and eaten. The nut remains in good condition for a long time and so it is quite conceivable that a colonist took a pocketfull to the new world.
I love your story and do not be too disheartened at the lack of germination of crab apple. This tree is found in isolated spots in English woodlands and these trees must have germinated from seed probably from fruit eaten by an annimal which was subsequently deposited with a load of fertilser. Some seeds need to be treated before they will germinate to break down their hard seed coatings. Try sandpaper.