I suppose it depends what you mean by 'oral histories'. A lot of the time, histories are blended with what outside scholars would consider to be myths and legends, and in some situations we'd find things like clans claiming descent from an animal ancestor with a slew of stories to back it up, despite modern science considering this generally impossible.

If you are in the market for indigenous American stories, native-languages.org is a pretty good resource that provides digestible overviews of various indigenous cultures as well as lists what we might consider their 'mythology'. It would perhaps be more accurately described as a nonprofit volunteer effort to build a compendium of various resources relating to indigenous tribal stories of all stripes, as well as linguistic material and comparative overviews of cultural elements.

This site is quite helpful indeed. One such link, for example, goes to this website and this story, which details the supposed split of the Comache and Shoshone nations. The site also is categorized by nation, so you can find which stories in particular you want to hear. Comanche? Inuit? Maya? They're all there.