In honour of Zeus, athletes at the first Olympic games were crowned with a wreath made from entwined wild Olive tree branches. It's still recognised as an emblem of the games today, as a symbol of Peace, Victory & Honour
If you give someone an Olive Branch you are giving the greatest gift, just like the Goddess Athena did....
Poseidon, God of Oceans and brother of Zeus, claimed possession of Earthly Attica by driving his trident into the Acropolis which then became a well of salt-water.
Athena, Goddess of Justice & Wisdom and daughter of Zeus chose not to retaliate with anger; instead she peacefully made an Olive tree grow next to the spring.
When Poseidon challenged Athena, Zeus formed a council of Deities to decide who should be enshrined in the city.
They decided Athena had given the city the greatest gift of it's first Olive Tree with it's abundance of fruits.
The city adopted the name of Athens and the Olive tree became a symbol of peace.