My own interest in this was aroused in 1986 when I met a farmer in Cornwall (SW Britain) on whose land lies the ancient Merry Maidens stone circle. He recounted that, when grubbing up an old earthen field boundary some years before, he had found a deeply-buried greenstone arrowhead which his son then took to school to show his teacher.
The teacher sent it to the British Museum for identification, and the reply returned that it was at least 5,000 years old and derived from specific rock deposits in Minnesota.
The possibility of this being a hoax was minuscule: there is little point planting evidence in a place where it is unlikely to be found or to be accepted as valid evidence – hoaxers need a pay-off. The farmer had little interest in prehistory – he was a classic farmer-type! What was interesting to me was that this evidence suggested west-to-east travel, from the ‘New’ to the ‘Old’ World, while one would tend to expect east-to-west travel, if anything. West Cornwall was frequented in ancient times by tin traders from the Mediterranean, particularly Phoenicians.
By the way . . . I vote for Amerigo. I volunteer at a Day Care center in my neighborhood to give a short history lesson to pre-schoolers. Amerigo is in my lesson plan . . . so it's my story and I'm sticking to it.