I only know of two, and as far as I know, they arent household herbs - but they ARE legal (at least in the UK).
Salvia - go to a headshop and get at LEAST 20x. Youll be tripping balls for the longest five minutes of your life, plus you only need a tenth of a gram, and you buy it in 1 gram vials.
Kratom - you buy it as ground up leaf material, and yes, it does work. Excellent for smoking just before you go to bed, its related to opiates. Dont believe people when they say that it makes you trip like LSD/mushrooms, because it isnt trippy in the least.