Isn't there a famous church in Scotland that has carved stone reliefs of Corn/Maize, except they were carved many years before the New World, and corn, were officially known about in the Old World.
I think ancient people did travel, after all, we have learnt they had number systems, watched the constellations, had crude but reasonable ancient maps, and genetics are discovering things all the time about the hereditary lines.
That would be Rosslyn Chapel - which has such a stunningly high level of detail in the stone carvings (NB well worth seeing) that it's not surprising that parts of it look a bit like something else. It wouldn't surprise me if parts of Rosslyn Chapel look a bit like Lady Gaga or an Xbox controller....
You can rent and stay in Rosslyn Castle, very close to the chapel. I stayed there once, and it was one of the neatest places I've been. The only shower is on the way to the dungeon.
So, I did a quick image search for Rosslyn Chapel maize and corn (see sibling comment), and I found nothing that looked convincingly like corn to me. There were a few things that looked a little like corn, but I would interpret them as other plants and/or bread.
I think ancient people did travel, after all, we have learnt they had number systems, watched the constellations, had crude but reasonable ancient maps, and genetics are discovering things all the time about the hereditary lines.