Mint will spread, I have some growing round my rose bushes and even if I mow it, it grows back. I like that I get the minty fragrance when I mow it. I think lavender's supposed to spread too but mine's not doing too well - I don't think I have very green fingers!
On the weed side of things, nettles, moss, and some kind of grassy stuff that's invading my veg patch seem the most resistant to my efforts to be rid of them...