I quickly emailed our son who lives in San Fran - he's a maths whizz - to ask
him for suggestions, and he said a pine cone and explained how the maths works
so I also thought daisy (none in bloom here right now) then protea (which we
had in a vase, we have protea growers up the road from us). Hope this is
acceptable for the "fibonacci" challenge!

[I found a cone, and here's how it displays the 'fibonaccii' expansion from the core]


Pinecones follow a Fibonacci sequence - as in the number of clockwise
and anticlockwise spirals are always adjacent members of the sequence
The sequence begins
1,1,2,3,5,8,13,21,34,55,....
Basically, each number is the sum of the previous two numbers