Stamps are great for crafts or decorating stationary before you send a letter. Here is a way that children can make their own stamps to decorate clothing, make a picture, or to make homemade wrapping paper to wrap a present in.
The best food to use when making your own stamps are apples and potatoes. Apples make a great design on their own cut in half vertically (for a traditional apple shape) or horizontally (for a circle with a star-shape in the middle).
With a potato, cut it in half and then make your design. Depending on the age of the children you may or may not want to let them execute this part. An easy way to make a design on the potato to use as a stamp is with small cookie cutters. Press the cookie cutter into the potato and the remove the excess flesh. You can make a positive or negative impression by removing the inside of the area or the outside of the area where the cookie cutter made its mark.
With tempura or another toxic-free paint, dip the apple or potato into the paint and have an extra piece of paper handy to dab off the extra paint. Make many different designs with the potatoes to great a variety of designs.
If you want to use the stamps as print making on clothing, buy some fabric paint at the craft store. If the paint is too thick add a few drops of water at a time until it is at a consistency that is easier to work with.
Be creative with your choices, you may also want to try carrots or another hard vegetable to see what kind of mark they leave. An alternative and less messy way to get the paint on the vegetable is to paint it on with a brush instead of dipping it into the paint.