We were created from the Earth, and with the grace of God placed in the Garden in order to do his work and help him in the creation and management of the universe, but due to our own nature we were to take a long, more difficult path then that. After our partaking of the Tree of Knowledge, our souls became seperated from God and the Garden (The Garden most likely being some state of primordial Heaven) so that we "Fell". In this action, we could no longer reside in Eden and lost it forever. Now to walk upon the Earth as a man and to know the pains and hardships of it, we were sent to "toil" and work upon the "Earth" .
This is probably the Spiritual Earth (Adamah) from which we were first created from/within - a place of Spiritual nuturality or emptiness that we may begin at to work on ourselves, and to rise up Closer to God till we may once again join him in his "Garden".

By the seperation from the Garden, we are by no means forcefully cast away from it...it is forever a place in the recesses of our minds and memories that we are connected to, and from earliest Childhood can sense in our subconcsious. One day again mankind shall regain God in the new Heaven (this time not a Heaven of Innocence, but a Heaven of Knowledge and Enlightenment).

The statement made by God as Adam and Eve left the garden "They are now like us" is one of much debate also - who is he speaking to? Most likely in my mind it is the Angelic host he speaks towards, his thoughts an emanating universal knowledge and understanding of the situation mankind now faced that the Angelic Host would hear. This gives us the idea that Angels were not originally created the same as Mankind in that they were innocent to Good and Evil, but were always aware of both. Angels are like mankind (post Garden of Eden) in that their state of Heavenly grace is based upon an educated and spiritual decision, as is the decision to reject God by those Angels who fall away from his light into darkness...