On one of the episodes of the treasure hunters on Oak Island they go to Europe in search of clues about the treasure being buried by the Templars. They go to some old church that was a Templar church built in 1100 or something - and they point out a fresco on the wall that they say is a corn stalk with the ears of corn.
But corn at that time only grew in the Americas - so proof that the Templars had been to America! (I don’t recall that they ever showed the corn stalk in great detail, or any real study of it.) But - makes for an interesting story.
I remember that as well (not from the Oak Island show) just not which church; there's also a (probably precolumbian) relief carving of a turkey in a church somewhere in Scandinavia, but that's hardly anomalous.
That church is Rosslyn chapel in Scotland, commissioned by Sir William St. Clair/Sinclair. The corn/maize bas reliefs are only one of many very interesting things about the chapel.
https://www.rosslynchapel.com/visit/things-to-do/explore-the-carvings/