“The flag of the United States shall be thirteen horizontal stripes, alternate red and white; and the union of the flag shall be fifty stars representing the fifty states, white in a blue field.”

“The flag should never have placed upon it, nor on any part of it, nor attached to it any mark, insignia, letter, word, figure, design, picture, or drawing of any nature.”

t-shirts, buttons, etc here: standard.threadless.com