I have to agree with 1320. That would have been awesome if it was whole. You should spend more time in that creek. Usually, where there is one, there is more that you didn't see.
It's sad that when I saw the title of this post, I rolled my eyes, due to the typical substance of such posts.
But this one is different, and that piece is definitely flaked. If you found it by a creek bed, I'd suspect it probably wasn't something from a gift shop at a museum, either.
My opinion is that this is likely a Native American artifact, yes.