Go to www.images.google.com and type in what images you would like to quilt. You can look up quilting stencils, but these are usually not free. On the left hand side of the screen, you can then narrow your search to what TYPE of image you are looking for. The options are Face, Photo, Clip Art, and Line Drawing. I'd go with Line Drawing. Click that. Browse around until you find the images you like.
I found my image from an online coloring book page. You could even use a real coloring book page. Here is the URL for my image: http://www.frontiernet.net/~goofis1/Images/Seasons/Spring/TulipDaisy.jpg
Print your image and use the print preview to get the size you need.
Set your stitch length to 1. This will help you remove your stencil easily afterward.
Now pin your image over your quilt sandwich.