Answer:
Two in a whole and four in a pair. Six in a trio you see. Eight's a quartet but what you must get is the name that fits just one of me.
I reach for the sky but clutch to the ground. Sometimes I leave but I am always around.
Weight in my belly trees on my back nails in my ribs feet I do lack.
I am the type of room you cannot enter or leave. Raise from the ground below I could be poisonous or a delicious treat.
I have every color but no gold.
The warmer I am the fresher I am.