The story of Adam, Eve and the Garden is an Eastern creation myth carried forward into Jewish oral history, written down following the Babylonian Captivity. The same story with variations is found in other traditions of what we in the West now call the Middle East. Its origin is probably the prehistoric Euphrates region.
Even the language of Genesis reflects the mythological nature of the story. Adam, for instance, is Adama, "Earth man" or "man of the dust." The text says he was created both male and female, i.e. he is a symbolic figure of the creation of the human race, not a person who ever in fact lived. In the story, Eve came later, made from Adam's rib, a literary theme also found in other Eastern traditions.
The Garden of Eden is likewise a symbolic representation of a mythologic time and place. It is a romanticized tribal memory of a preagrarian hunter/gatherer society. The Hebrews, or people who later became them, were surely somewhere at the time they lived off the fruits of the land without having to farm to have food or to be crowded into cities to survive, but as such societies in historical times show it could hardly have been paradise. Mythologies tend to weed out the bad and highlight the good of those generational memories, and so by the time the stories of Genesis were told in the way later written down so that we today can read them they had forgotten the disease, violence, periodic hunger, short lives, and brutality characteristic of such societies.
None of this is intended to belittle the faiths of Jews, Christians (such as I), Muslims, or any others incorporating the Eden myth. It can be taken as a counter to a superficial reading of the Bible, which can be taken literally to no greater an extent than the similar records of other cultures. Adam, Eve, and the Garden of Eden never existed in fact. There is probably a germ of truth in the stories. There usually is in mythology. Exactly where that germ lies, however, is something we will never know.