http://en.wikipedia.org/wiki/World_Vegan_Day:
World Vegan Day is an annual event celebrated on 1 November, by vegans around the world. The Day was established in 1944 by Louise Wallis, then President & Chair of The Vegan Society UK. 2011 marks the 67th anniversary of the term 'vegan' (and thus the verbally clarified concept of 'veganism' and of the Vegan Society).
The Vegan Society of Japan has a page that explains the evolution of the use of the sunflower image as the logo for The Vegan Society: http://vegansociety.jp/vegan-logo/evolution/
