I had not heard about this challenge before today. I just discovered it this morning while reading Bridgette Guerzon Mills' blog.
There was no time left for a big search, but I found these pictures in my folders...
Mushrooms in the nearby woods
Back from the market, some day in June I guess
Two pictures taken in 2009, in the mountains North of Kyoto
たこ焼 (Takoyaki) lanterns, in Kyoto
Next month colour will be Orange. I'll start looking for it tomorrow!