I thought I would poll other, more famous authors, who have surely heard this question one million times.
Stephen King (from Stephenking.com)
I get my ideas from everywhere. But what all of my ideas boil down to is seeing maybe one thing, but in a lot of cases, it's seeing two things and having them come together in some new and interesting way, and then adding the question, "What if?" "What if" is always the key question.
JK Rowling (from jkrowling.com)
“It was 1990. My then boyfriend and I had decided to move up to Manchester together. After a weekend's flat-hunting, I was travelling back to London on my own on a crowded train, and the idea for Harry Potter simply fell into my head.
I had been writing almost continuously since the age of six but I had never been so excited about an idea before. To my immense frustration, I didn't have a pen that worked, and I was too shy to ask anybody if I could borrow one…
I did not have a functioning pen with me, but I do think that this was probably a good thing. I simply sat and thought, for four (delayed train) hours, while all the details bubbled up in my brain, and this scrawny, black-haired, bespectacled boy who didn't know he was a wizard became more and more real to me.
Perhaps, if I had slowed down the ideas to capture them on paper, I might have stifled some of them (although sometimes I do wonder, idly, how much of what I imagined on that journey I had forgotten by the time I actually got my hands on a pen). I began to write 'Philosopher's Stone' that very evening, although those first few pages bear no resemblance to anything in the finished book.”
Jerry Spinelli (from jerryspinelli.com).
Jerry gets his ideas from everyday life, memories, his imagination.
Linda Sue Park, (from lspark.com)
From the idea store, of course!
Just kidding. I get ideas from reading books and articles, listening to people talk, watching TV and movies; from things I see and hear; from sitting around daydreaming. Ideas are everywhere: important thing is to find the ones that interest you.
What Linda Sue Park does not say is her husband is a journalist. She got her idea for "A Long Walk To Water" from a young man her husband introduced her to.
By now you are getting a theme. Writers do not have any secrets about where the ideas come from. They come from observations of everyday life, people, experiences. You don’t have to live an extraordinary life to write a great story. You just have to use your imagination and ask yourself, "What if?"