You can use any of these graphics for your games. All graphics are free for educational use and are courtesy of doodlipoop.com.
/media/graphics/game_hero.png
/media/graphics/game_good.png
/media/graphics/game_bad.png
/media/graphics/graphic-02.png
/media/graphics/graphic-03.png
/media/graphics/graphic-04.png
/media/graphics/graphic-05.png
/media/graphics/graphic-06.png
/media/graphics/graphic-07.png
/media/graphics/graphic-08.png
/media/graphics/graphic-09.png
/media/graphics/graphic-10.png
/media/graphics/graphic-12.png
/media/graphics/graphic-13.png
/media/graphics/graphic-14.png
/media/graphics/graphic-15.png
/media/graphics/graphic-16.png
/media/graphics/graphic-17.png
/media/graphics/graphic-18.png
/media/graphics/graphic-19.png
/media/graphics/graphic-20.png
/media/graphics/graphic-22.png
/media/graphics/graphic-24.png
/media/graphics/graphic-25.png
/media/graphics/graphic-26.png
/media/graphics/graphic-49.png
/media/graphics/graphic-27.png
/media/graphics/graphic-28.png
/media/graphics/graphic-29.png
/media/graphics/graphic-30.png
/media/graphics/graphic-31.png
/media/graphics/graphic-32.png
/media/graphics/graphic-33.png
/media/graphics/graphic-34.png
/media/graphics/graphic-43.png
/media/graphics/graphic-44.png
/media/graphics/graphic-45.png
/media/graphics/graphic-46.png
/media/graphics/graphic-47.png
/media/graphics/graphic-48.png
/media/graphics/graphic-49.png
/media/graphics/graphic-50.png
/media/graphics/graphic-51.png
/media/graphics/graphic-57.png
/media/graphics/graphic-56.png
/media/graphics/graphic-35.png
/media/graphics/graphic-36.png
/media/graphics/graphic-37.png
/media/graphics/game_wall.png
/media/graphics/graphic-54.png
/media/graphics/graphic-38.png
/media/graphics/graphic-39.png
/media/graphics/game_tile.png
/media/graphics/graphic-40.png
/media/graphics/graphic-41.png
/media/graphics/graphic-42.png
/media/graphics/graphic-01.png
/media/graphics/graphic-52.png
There are many other online resources for game art. A very popular resource is OpenGameArt.org