Well, technically I sold one on a stock site for a couple of dollars 3 years ago, but that didn't count for much in my mind. I sold one of my earliest challenge entries that had scored at the higher side of mediocre. But you know what? There aren't nearly as many good photos of copier drums available as there are flowers, bugs and gorgeous models. I was paid $150 for it's use in a textbook. Got the check in the mail today. :-}
Where did you go through to sell it....website, word of mouth, etc.
They saw my photo on Flickr, probably found through a web search. Since it wasn't something already being used in advertising, they contacted me asking to use it. Since this was a for-profit usage, I asked for whatever they felt was a fair payment. Had to fill out some vendor forms and wait several months for it however.
I was at a photography workshop a couple of weeks ago, when the speaker was talking about receiving a check for about $ 600 that week for a photo for a Science textbook. He had taken the photo in the 80's, it was on a stock site. (I think he said the payment was for 3 separate sales.)
That's sweet!!! Text books are the way to go. My mom wrote some poems, got paid a small amount (very small amount) and got over $1000 for it to be reprinted in text book anthologies.
Some if my best sales have been for text books, and the subjects have been so mundane: FL license plate, plug with a bent prong, etc. These are nice for the money (!$100 - $200), but I love it when my art photos sell, even though the money isn't quite as good.