Answer:
What is used by man, tossed by trees, everywhere but unseen?
Every country has one, though we are not the same. Waving to our citizens, throughout the wind and rain. What is it?
It can be done to buttons and shopping carts. What is it?
Sitting down you have it, Standing up you don't.
Timid or weak people are said to not have these.
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.