A nice little overview from About.com featuring some basic info on fun things like humans with horns, giants, elongated & fat skulls, shit like that.

There’s also mention of a race of giants in Native American legend, called the Si-te-cahs. I never heard of them, and looked up some info about them. They are possibly connected to a find which reportedly occurred in Iowa, called the Kossuth Giants:

When the light from the first torch penetrated the gloom of the ancient structure, Albert Grosslockner gasped at what he thought were seven huge and exquisitely detailed statues seated in a ring around a very large and deep fire pit. Moving closer, he realized that the figures were not carved of stone, but were in fact the mummified remains of some giant humanoid race. Could what they found be in fact a prehistoric burial vault for some pre-human creatures or was it a prison designed to hold some freakish aberration of nature? The figures, were each fully ten feet tall even when measured seated in their cross-legged positions. They all faced into the circle with arms folded across their legs. Upon close examination it was seen that they had double rows of teeth in their upper and lower jaws. The foreheads were unusually low and sloping, with exceedingly prominent brows. The skin of the mysterious giants was wrinkled and tough, as though tanned, and the hair of each of them was distinctly red in color. Their faces, still very expressive even in death, taunted the scientists with their silence.

This other site has a sketch of the giant’s tomb, as well as a photo of one of the Kossuth giants.