Answer:
This is rectangular, hollow and has a lid, and where you’ll find it you might wonder, it is just six feet under. What is it?
Whiling away the hours of flowers, Walking through fields of gold. Preening and pruning in lights fading hours, For petals to freeze in the cold. What is it?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.
I am never quite what I appear to be. Straight-forward I seem, but it's only skin deep. For mystery most often lies beneath my simple speech. Sharpen your wits, open your eyes, look beyond my exteriors, read me backwards, forwards, upside down. Think and answer the question...
What looks back but cannot see?
I will disappear every time you say my name.