Native American Genocide - A lie I hear repeated too often by the ignoranti, is that Americans committed gennoacide against Native Americans... like they used smallpox laden blankets as an example of that: we intentionally exterminated them. Only if you know that facts, that wasn't us -- it was one letter from a Brit to a Brit about maybe doing it, long after 90% of the indigenous people had been wiped out.
Gentle savages - Another lie I hear repeated is that the Native Americans were gentle or weren't savages. Um, yeah, not so much. There certainly were less savage tribes, but there were many violent tribes that did horrible things. Sometimes retaliation was unfairly put on all tribes (or the wrong tribes) for the crimes of some: but a lot of the violence against tribes was warranted by past behavior, even if not directed at the correct tribe.