Writing a Poem

What's weird about writing:  when I start a poem with a few words, it already feels like I'm following someone's footprints.  Like the poem is already finished and all I have to do is complete it by writing down previously written words.  I know how some people say a poem flowers out from the first word.  For me, it's like the rose, dandelion, or stinkweed were already there.  I write quickly, but sometimes I can't make out a word, and that's when I feel like I have a choice; there might be a slight deviation.  Some poems I've written have always seemed to have existed.