Well, there are some legal psychoactive plants like salvia divinorum (a powerful hallucinogen, up there with LSD) but that isn't sold as "legal buds", or at least it shouldn't since it doesn't come in buds and its effects are nothing like weed. In fact, there's no other plant you can smoke to get high the way you can with weed, and the things that come close (like opium) are illegal as well. Try to find out what's in the legal buds if you're curious. If you can find out the names of the plants, a little research can tell you whether they can give you a buzz, and if you can't get the names of the plants, well, I wouldn't smoke it if I didn't know what it was.