Answer:
A shimmering field that reaches far. Yet it has no tracks, And is crossed without paths.
What an fill a room but takes up no space?
You heard me before, yet you hear me again, then I die. Until you call me again.
I have one, you have one. If you remove the first letter, a bit remains. If you remove the second, bit still remains. If you remove the third, it still remains.
Talks like this, a green wise man does. Guess my clue, you will.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.