Every author is asked this question more than once: Where do your get your ideas?
On one author's website (can't remember who it was), he answers this question simply: From his head.
A valid answer, and true. But I don't think that's the kind of answer a person is looking for when asking where our ideas come from. Maybe the question should be rephrased, "What makes an idea take root in your head?"
Sometimes, especially when I am writing with Corey, an idea takes root after much brainstorming. I'll dig around the storage rooms in my brain in search of something worthy of planting. The first story Corey and I ever wrote together, Porcupine's Painting, came about this way, as do many of our other stories. But when I try to do this on my own, the ideas don't take root as easily.
It's more fun--and usually more productive--for me when an idea seems to hit me out of nowhere. It might be sparked by something one of my kids say, like when Daughter #2 commented that the dragon I had drawn for her was lonely (my first MG novel). Or something that makes me laugh, like when my husband said something funny while making a ham sandwich (pirate pigs picture book). Or when an image appears in my mind, like when that persistent tiger visited me one night as I teetered on the edge of sleep (current WIP, novel-in-verse). Where did the tiger come from? I don't know, but he must have been lurking in my brain somewhere.
Then there is the "writing prompt." A regular JOP (junk on paper--or 'puter) exercise will often sprout into a real idea. At the very least, it's a good way to practice for when I do get a real idea.
Most common for me is getting a beginning of an idea. For example, I once had an idea for a story about a speedy turtle. I wrote two paragraphs of that story before getting completely stuck, and no amount of vacuuming was helping. So the story sat for months and months until, finally, the rest of the story just came to me.
Rejections can spawn ideas too! I once submitted a hockey poem to Highlights (I wrote the poem after watching a hockey game). They considered it, but ultimately rejected it. I thought, "If they liked one active sports poem by me, they'll probably like another one. " So I wrote a poem about baseball, sent it to them, and--SOLD!
It doesn't always work out quite so nicely. Some ideas spring up at first and then quickly wither away. Some stay dormant so long that I think they're dead--but it turns out they were just waiting for spring. Others find a nice, fertile spot in my brain and grow and grow until they finally become full-grown poems and stories. What makes these stories take root? I think it is mainly because of the love and determination of the writer.