Embellishing rocks seems to be quite popular. Some people paint them, some people embroider them, some people felt them, some people wrap them in lace, some people wrap them in polymer clay, some people crochet them and some people bead them.
And if you want them to be fragrant, check back the previous mentioned Fragrant Rocks.
I never did anything with rocks, because I’m living on sandy ground ;-)
But all those rocks rock ;-)