A story about Merlin Exploring the New World?

Cafe Society
1

Does anybody remember a story about Merlin and a band of knights who travel to the Americas long before Columbus? I remember they explored much of the eaastern and southern US, and had a bloody battle with what was apparently the Aztecs or other tribe in Mexico/Central America.

Ring a bell?

2

King of the World’s Edge. As I recall, Merlin and the druids were depicted as tricksters, and they discovered a race of sentient amphibians. I had a paperback with a cover illustration of a couple of these creatures swimming near a large wooden ship.