After strolling the area for treasures, set up your blanket and set out to make your art project out of the rocks you have collected. Maybe make jewelry, decorate a bird house, or just paint the rocks.
Make sure you bring scissors, glue, markers, string, paint, paper, some jewelry items to glue the rocks to or any other items you might need for your project and a piece of cardboard for them to work on.
This is a great gift-making idea for the grandparents. Don't forget to bring the camera to take pictures as they create their masterpieces and maybe to use as your family picture or next year's calendar photos. Top it off with a contest of who can stack the most rocks without falling while you are packing up the supplies and you have had a great day at the park.