Writing a book

I'm starting a new project, but not a knitty one.  I'm writing a book, or at least trying to.  I've made several trips to my home town this summer; my parents still live there.  Due to road constitution I've had to take a different route though the back roads and farm country and I've been hit with a very severe case of nostalgia. As I drove though the farm country that I couldn't wait to get away from as a kid, I've come to realize just how much I miss it.  My book will be memories of growing up in rural Wisconsin, with my own experiences and some of my Dad's stories that he's shared about his childhood.  I have a feeling his will be more entertaining than mine.

I'm having a problem though.  When I sit down to write, I have a memory in mind that I want to write about, but the words just don't flow.  I can see it in my head like I'm watching an old home movie, but I can't describe it.  Then when I'm in bed and I think about what I want to write, the story just flows beautifully and I think I have to remember this, but it's gone by morning.  I'm a much better writer in my sleep.