Please have a look at some of the puerh beengs. On the wrapper, there is a green chop/stamp. Not sure what it is but do you know when that chop was initially used?
Pray tell if know.
Do you mean the "tea" Chinese Character surrounded by the Zhong character? That was created when Chinese industry went fell under the "Peoples" jurisdiction. It represents The character represents tea of course and the Zhong represents China. It symbolizes Chinese tea being spread across the world. This is why the Zhong character is in the shape of a circle, representing earth.