The Tree in Genesis 2 is symbolic. It encapsulates works brought about by the word/spirit/power. The tree of knowledge is, therefore, works brought about by knowledge. By extrapolation, the tree of knowledge of good and evil constitute works brought about by good
(righteousness of faith brings about good report) and evil
(sin brings about evil report).
The Tree
Mankind start out naturally as
"living souls" and are expected to end up spiritually as
"quickening spirits" who must bear fruit. Mankind works and is a living work by the Word of God. Jesus Christ made a blind man to see men in both ways. Mark 8:24-25 declares:
And he took the blind man by the hand, and led him out of the town; and when he had spit on his eyes, and put his hands upon him, he asked him if he saw ought. And he looked up, and said, I see men as trees, walking. After that he put [his] hands again upon his eyes, and made him look up: and he was restored, and saw every man clearly.
The Fruit
Fruit results from a tree
(works brought about by the word/spirit/power) and constitute the meal
(meat, food). According to John 4:34, Jesus Christ declared:
Jesus saith unto them, My meat is to do the will of him that sent me, and to finish his work.
For example, fruit of the Spirit result from works by the Spirit. Love, joy, peace, longsuffering, gentleness, goodness, faith, meekness and temperance are spiritual food from the Spirit given us to eat.
The Tree of Knowledge of Good and Evil
This tree encapsulates all good and evil works of that knowledge
(a form of spirit) musters. Because of its evil component, whosoever eats the fruit dies.
In the Garden of Eden, works by the Word/Spirit/Power of God were the trees. Fruit from these trees were/are good, acceptable and perfect for consumption.
The Devil
(Satan) was also present in the Garden. Remember that he
(the Devil), formerly an angel of God, has a limited knowledge of God as well as the knowledge of evil. His works
(tree) from his hybrid knowledge of good and evil rendered as the
Tree of Knowledge of Good and Evil.
That is how come Satan's tree could be found in the Garden of Eden. It was the least of all the trees because Satan's presence
(including his works) in the Garden was subtle in every sense and meaning.
Fruit of the Tree of Knowledge of Good and Evil render as hate, sorrow, strife, inpatience, unruly behavior, sin, faithlessness, pride and intemperance. Through Adam and Eve, mankind tasted and received these things from Satan into their souls.