Tux Paint is a free drawing program for Windows designed for children (age 3 and up). It has a simple, easy-to-use interface, fun sound effects and a cartoon mascot who helps guide children as they use the program.
It provides a blank canvas and a variety of drawing tools from paint brushes, line and shape tools, text tool and a "magic" special effect tool to add things like grass, bricks to blurring parts of the picture, all to help your child be creative.
You can also install Tux Paint Stamps which installs a set of images that can be used with the stamp tool in TuxPaint