Ok, here is a list of some legal herbs I have tried, and a brief description:
Leonurus Sibiricus (Marihuanilla): Pretty much worthless, very faint buzz and very unpleasant smoke. Nothing like mj.
Leonotis leonurus (Wild Dagga): Better than the forementioned marijuanilla (they are cousins) but still pretty mild. A light buzz that is hard to sustain. Still not really like mj, but for some may be worth experimenting with.
Yohimbe: A very potent stimulant that will wire you up for a long time. Not for the faint of heart, literally.
Betel Nuts: Very popular in other parts of the world, but I don't really enjoy chewing them. They gave me a nice buzz the first time I tried them, kind of like chewing tobacco for the first time, but nothing after that. These are supposed to have a stimulating effect. There is a very good product that makes these much more palatable:
http://basementshaman.com/betnutsmarch.html
Wormwood: Don't even bother unless you can get real absinthe...the stuff they are selling here in the states is a joke compared to the real thing. The herb used on its own is of no value to me.
Amanita Muscaria: This is actually a mushroom, and I have had some excellent experiences with them. This one requires a bit of discipline and understanding before you go there...do your research. I cannot really explain the experience, it is entirely different than the effects of psilocybin, LSD or mescaline.
Hope this helps! Good luck and BE CAREFUL.