This could also be called "flower painting" or "flower squishing". Take your pick!
1. Choose your flowers. I've tried it with lots of different flowers, and honestly most of them are disappointing. But! Violas almost always work beautifully, so I highly recommend using them.
Pick the viola close to the bloom so there isn't much of a stem, and lay it face down on your paper.
Lay another piece of paper on top of it, and start rubbing! Squish, rub, press. Use the edge of your nail. You want to get the juice out of the petals, but don't just mush it around. Try to keep the flower from moving.
Now peel away the paper and the bruised flower, and repeat as many times as you wish with fresh violas!