September 24th - 30th Edition
The coin could have been in Cabot's own pocket, for all we can tell—predating him doesn't mean its presence here predates his, but that WV petroglyph is INTERESTING!
Someone on Facebook mentioned the lack of non-native foodstuff (either crops or livestock) as a strike against the "Old Irish" story. But this also is somewhat contingent on WHY the Europeans (or other outsiders) came: if they came to trade and go back home, the artefacts would be different from those of a military conquest or different again from a colonization settlement.
In the case of the Christmas Day ogham, it seems to serve two purposes: Christian iconography and an astronomical calendar. It can thus likely be supposed that these Irishmen, if the carvings are authentic, were there as missionaries and perhaps educators to the natives. It is not unheard of for those in such fields to adopt local diets and other material culture IOT better integrate socially with their congregations, and such a practice would leave far fewer archaeological relics than a colonizing settlement or a military garrison.