Caddo

(map)

My source for this myth gives as reference only "Retold from various sources." However, it is a variant of a well-attested Wichita myth.

A woman gave birth to four monsters. Though advised to kill them, she let them grow. They grew quickly and acted evilly, and before long they were too large and powerful to kill. They kept growing. One night they came together in the camp with their backs together and grew together into one creature, which grew tall enough to touch the sky. Most people took refuge at their base, where they couldn't bend over and reach them; others were caught by the monsters' long arms and eaten. One man who could see the future heard a voice telling him to plant a hollow reed. He did so, and it quickly grew very big. The voice directed the man and his wife to go naked into the reed, taking pairs of good animals, when they see all the birds of the world flying south. The sign came and they entered. Rain came, and waters rose to cover everything but the top of the reed and the heads of the monsters. Turtle destroyed the monsters by digging under them and uprooting them. They broke apart and fell in (and thus formed) the four cardinal directions. The waters subsided, and winds dried the earth. The people and animals emerged onto a barren earth, and the wife wondered how they would live. The man said, "Go to sleep." Four times they slept, and each time they woke there was more growth around them. After the fourth night, they awoke in a grass hut, and there was a stalk of corn outside. The voice told them corn was to be their holy food. If they plant corn and something else comes up, then the world will end. The voice didn't return after that.

Erdoes & Ortiz, 1984, 120-122.