About twice a week, someone asks Liz West’s permission to use one of the nearly 12,000 images the amateur photographer has uploaded to the photo-sharing site Flickr over the past decade.

Ms. West is usually happy to comply. One woman in England created notecards using her floral pictures and sent her 100 cards in appreciation, she said. Vermont Castings, a stove and fireplace maker, used one of Ms. West’s photos on its website and shipped her a small stove as a gift.

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