Looking for something else completely, I happened upon this 'free photo sharing' site, and sure enough, stock images are being offered there 'free'.
E.g. http://www.4shared.com/photo/Ckl0QqD6/freegreatpicturecom-694-jumpin.htm
is on SS:
http://www.shutterstock.com/pic-2790314/stock-photo-goldfish-is-jumping-picture-was-made-in-a-studio.html?src=eDZATg8CksNkgNykzBSpkQ-1-3
and DT:
http://www.dreamstime.com/stock-images-jumping-goldfish-image2020144

Clicking the download button doesn't seem to let you download the image AFAICS, but clicking the enlarge button gives you a nice big size to steal as you wish.

Anyone who knows the author might like to contact him; otherwise, you might like to check for your own images.

Another example:
http://www.4shared.com/photo/3oDHI2RN/lettuce.htm
stock image from:
http://www.dreamstime.com/stock-photography-chinese-lettuce-image1016312
http://www.featurepics.com/online/Chinese-Lettuce-Picture356889.aspx
etc