There are many more copyright free images available from sites on this list. (Note this is a Diigo list, Diigo makes it easy to store and organise your bookmarks online which means you can access them wherever you are).
Note that it is usually a requirement to give correct attribution when you use a copyright free image. The above image was found by searching on flower in a Google custom search for copyright free images.
Note that one of the sites on the list is The Commons from Flickr where you can search for images you want. Suppose we want an image of a red flower, entering red flower in the search box returns many images, the first of which is shown below. It is particularly easy to generate code for a flickr image with correct attribution to embed in your site by using ImageCodr. Simply enter the Flickr URL of the photo you are interested in on the Get code! page and the correct html code will be generated for you. The result for this example can be seen below.
Note that you can choose the size, perhaps we might want medium size!