Open Clip Art is a resource for Public Domain clipart There are no copyright limitations. There are no requirements to include attribution of the clipartist. But for information, the sample on the left is by kattekrab
You can even put the clipart into your own drawings without any affect on the copyright or license of your work. The clip art can be edited and modifed and redistributed under your own terms.
Alternatively, submit your own artwork to the site!