DaRC wrote:There is no evidence of a European culture surviving in mainland America before Columbus AFAIK.
(after I composed this, I see that you say "mainland"...Newfoundland is another island, of course)
L'Anse aux Meadows from the French L'Anse-aux-Méduses or "Jellyfish Cove") is an archaeological site on the northernmost tip of the island of Newfoundland in the Canadian province of Newfoundland and Labrador. Discovered in 1960, it is the only known site of a Norse village in Canada, and in North America outside of Greenland. The site remains the only widely-accepted instance of pre-Columbian trans-oceanic contact and is notable for possible connections with the attempted colony of Vinland established by Leif Ericson around 1003, or more broadly with Norse exploration of the Americas.
The village lasted for about 8 years as a base camp for explorers, and they didn't get on well with the locals...probably Beothuks. How much of their "culture" survived, or what cultural exchanges there were is hard to say. I'm sure the Beothuks had a "take away" meeting after the last longboat pulled away.