How would i make a photo collage/mosaic in the shape of a peace sign/symbol?

i want to make a photo collage/mosaic/thingy in the shape of a peace sign (the actual symbol, not the hand gesture), but i want the photos to actually fit inside the perimeter of such. meaning that i do not want the edges all jagged and i want the peace sign to be completely filled with the image/images. if programs are necessary, please only list the free ones :)