Where do ideas come from?

Originality.. I think thats the biggest thing I'm struggling with right now. I know that all the books and things I've read create a treasure trove of ideas and scenarios but how can I put my own story down when all the others are crowding in my head. Names, places, plots its like there is so much in my head that I can't find something that I can actually sit down and write about. I think that stems from the fear of being regected I know that not all ideas are A+ but who wants to be told that what they wrote sucks! Not me thats for sure so I guess the thing now is to get over that fear and just write what comes into my head without bias of the words or ideas. wish me luck.