Basically had the same thoughts as cricket3, no specific book reference.

For hands on work, the Fibonacci sequence can be seen by counting the petals in each ring of a flower. I think corn kernel rows on a cob also are good for it. The Golden Ratio/Golden Number/Phi is also a fun discoverable number as it is rooted in the Fibonacci sequence, and it shows up in many places in nature (such as the human head width to height ratio.)