I dont have any sources, but there have been accounts of giant skeletal remains being found in North America since pretty much the beginning of our nation. Several were in newspapers. True or hoax? Dont know. The common theme with most of the remains was that the Smithsonian took them and they were never studied or displayed.
Why wouldn't there be studies, documentaries, and displays? Well, they were either hoaxes, or those institutions had reason to keep that shit suppressed. Best guess, is that it upsets the historical record and lots of religious people.