For example, above is a thumbnail of one of my mine, a Viceroy butterfly. Since the photos are copyright-free, you can use them however you wish.
This is a free 105 page PDF you can download that has 60 copyright-free photos donated by ten fiber artists. They are Dena Crain, Claire Fenton, Martha Ginn, Loreen Leedy, Linda Matthews, Christine Predd, Kim Ritter, Louise Schiele, Emmie Seaman, and Virginia Spiegel.

Click here to download Inspired by Photos.

In case you’re interested, here is a little more info about my images:

#1 A Viceroy butterfly on a buddleia bloom.
#2 A treefrog in a birdhouse.
#3 An Atlas silk moth
#4 A waterfall in the butterfly house at the Natural History museum at U of Florida, Gainesville.
#5 Spring flowers somewhere in Switzerland.
#6 A slash pine.

The background colors above were tweaked in Photoshop using the Image>Adjustments>Replace Color feature several times in different areas of the image. There are several tutorials on my studio blog about various ways to adjust images. On the blog sidebar, look under Topics for Photoshop tip.