Fibonacci sequence in nature, truth or just wishful thinking?
As far as I remember, Fibonacci patterns emerge in plants from hormone gradients. I.e. an apical meristem forms a leaf where the auxin concentration is highest, and already existing leafs lower auxin concentration, leading to some negative feedback.

See e.g.
http://www.sciencedirect.com/science/article/pii/S1360138507000581

or http://en.wikipedia.org/wiki/Phyllotaxis