Why does Krishna wear peacock feathers?
It should be understood that Krishna is a person. He has His likes and dislikes, just as we all do. He likes it when His devotees offer Him things out of love.
When He plays in the forest with His friends, He decorates Himself with the feathers left from the peacock. Once Lord Krishna created a wonderful festival in the forest by playing on His flute. In gratitude, the peacocks offered their feathers as dakshina (tribute). They requested the Lord to wear them in His turban and He agreed.
Here's a recording of a dear Godsister of mine relaying the story of why Krishna wears a peacock feather. Please listen. It is very wonderful: Why Krishna Wears Peacock Feathers
Hope this answer is helpful and you enjoy the recording.