If you want printable Hidden Object games for kids check out www.highlightskids.com you can print right from the web.
Where Do I Find Printable Hidden Object Games For Kids?
Where to find free hidden objects worksheets for children
You don't say which age group you want these worksheets for, but am hoping at least some of these suggestions will help!
2. Exploring Nature Educational Resource
3. smschool.org
4. docstoc.com
I haven't included an image with this one, as you are only allowed to make paper copies of Liz Ball's images, not virtual ones.
Other good sources of free hidden object or puzzle worksheets for kids include (click on the links for more info):
Check out www.scavenger-hunt-guru.com for some creative ideas and lists.