Razzle,
Awesome that you have a grandmother to sew for you. Unfortunately I don't believe that there are a many new patterns out of that style, they were very popular 10-15 years ago. However, here is a link to ebay listing many of the hat patterns that they have available, many of which are out of print. Check it out. The great hing about sewing your acessories is that you can have many hats of different colors once you find a pattern that you like. Hats are fairly easy to sew. Have fun.
As far as colors go, I would stick with a solid color for the hat with colorful accents (handband, etc.) But that's my 2 cents worth.
Miss D.
http://search.ebay.com/search/search...ing&category0=