retold by Richard L. Dieterle
Version 1. When the Medicine Rite was first created by the good spirits, each of them contributed something that would help the humans overcome the evil spirits. After all the spirits had made their contributions, only then did Grandmother (Earth) come forward and speak to Hare: "Look at my breast, grandson." Then, unexpectedly, there grew from one of Grandmother's breasts a plant that no one had ever seen before. It grew immediately from her nipple into a full stalk with ripe ears of corn ready to eat. "This, grandson," said Earth, "is maize. The two-legged walkers may eat its corn forevermore." 
Version 2, by Oliver LaMère. "From one of the two breasts of Mother Earth sprang a plant which grew and bore fruit — the corn plant to nourish the Indian with its ears of corn. From the other breast sprang the tobacco plant used by the Indian as a sacred offering to greater and lesser deities." 
Commentary. "ripe ears of corn" — when the corn is white and milky in the center, it is time to harvest the crop.  This is one of the reasons why maize is associated with the breast of Grandmother.
"Version 2" — in the way of a preamble, Dorothy Brown had this to say about the story:
The Winnebago Indian name for corn is wiča-was. This tribe raised many bushels of corn at their different southern Wisconsin villages in the thirties and in later years. They had a number of different kinds of corn, the principal kinds being a yellow, and a red corn and sweet corn. Today in Wisconsin and Nebraska they have a white and a blue flint corn. The late Oliver Lamere, a Winnebago, once stated that they had no fewer than fifty different ways of perparing and using corn. He furnished this Winnebago corn myth.
By "in the thirties" she meant the 1830's, since she adds "in future years," when her article was submitted in the 1930's.
Links: Maize, Earth, Hare.
Stories: about maize (corn): Maize Comes to the Hočągara, The Medicine Rite Foundation Myth, The Green Man, Grandmother's Gifts, Waterspirits Keep the Corn Fields Wet; featuring Grandmother Earth as a character: Medicine Rite Foundation Myth, Grandmother Packs the Bear Meat, Grandmother's Gifts, Owl Goes Hunting, Hare and the Grasshoppers, Hare Acquires His Arrows, The Plant Blessing of Earth, Hare Visits the Blind Men, Hare Visits His Grandfather Bear, Hare Visits the Bodiless Heads, Hare Burns His Buttocks, Hare Gets Swallowed, Hare Kills Wildcat, Hare and the Dangerous Frog, Hare Retrieves a Stolen Scalp, Hare Recruits Game Animals for Humans, The Necessity for Death, Hare Secures the Creation Lodge, Hare Steals the Fish, Hare Kills Sharp Elbow, Hare Kills Flint, The Gift of Shooting, The Creation of the World, The Creation of Man (vv 4, 6), Hare Establishes Bear Hunting, Redhorn's Father (?); featuring Hare as a character: The Hare Cycle, Medicine Rite Foundation Myth, The Necessity for Death, The Mission of the Five Sons of Earthmaker, Hare Acquires His Arrows, Hare Retrieves a Stolen Scalp, Hare Recruits Game Animals for Humans, Hare Kills Wildcat, The Messengers of Hare, Hare Secures the Creation Lodge, Hare Kills Flint, Hare Kills Sharp Elbow, Hare Visits His Grandfather Bear, Grandmother Packs the Bear Meat, Hare Visits the Bodiless Heads, Hare Visits the Blind Men, Hare Kills a Man with a Cane, Hare Burns His Buttocks, Hare Gets Swallowed, The Hill that Devoured Men and Animals, Hare Establishes Bear Hunting, Grandmother's Gifts, Hare and the Grasshoppers, The Spirit of Gambling, The Red Man, Hare Steals the Fish, The Animal who would Eat Men, The Gift of Shooting, Hare and the Dangerous Frog, Thunder Cloud is Blessed, The Coughing Up of the Black Hawks, The Animal Spirit Aids of the Medicine Rite, The Petition to Earthmaker; pertaining to the Medicine Rite: The Medicine Rite Foundation Myth, The Journey to Spiritland, Battle of the Night Blessed Men and the Medicine Rite Men, Holy Song, Holy Song II, The Necessity for Death, Hog's Adventures, Great Walker's Warpath, see also Stories from Jasper Blowsnake's account of the Medicine Rite.
A variant of this story is told in The Medicine Rite Foundation Myth.
Themes: spirits come together to pool their resources to give humans power over their enemies: Waruǧápara, The Children of the Sun.
 Oliver LaMère and Harold B. Shinn, Winnebago Stories (New York, Chicago: Rand, McNally and Co., 1928) 104-105. Informant: Oliver LaMère of the Bear Clan. Paul Radin, The Winnebago Tribe (Lincoln: University of Nebraska Press, 1990 ) 309.
 Dorothy Moulding Brown, "Wisconsin Indian Corn Origin Myths," Wisconsin Archeologist, 21, #1 (1940) 19-27 .
 Sally M. Hunter, Four Seasons of Corn: A Winnebago Tradition (Minneapolis: Lerner Publicatons Company, 1997) 25.