Answer:
Forward I’m heavy, but backwards I’m not.
Four of us are in your field, But our differences keep us at yield, First, a one that is no fool, Though he resembles a gardener’s tool, Next, one difficult to split in two, And a girl once had one as big as her shoe, Then, to the mind, one’s a lovely bonder, And truancy makes it grow fonder, Last, a stem connecting dots of three
A serpent swam in a silver urn, A golden bird did in its mouth abide, The serpent drank the water, this in turn, Killed the serpent. Then the gold bird died.
What begins and has no end? What is the ending of all that begins?
Three little letters, a paradox to some. The worse that it is, the better it becomes.
I’m grown from darkness but shine with a pale light. Very round I am and always a lady's delight.