Most legal herbs that are entheogenic in nature (mind altering substances) are extremely poisonous, and I wouldn't give them to just anyone. I would rather someone not kill themselves thinking they can just ingest whatever and go enter trance and achieve an OBE (well an OBE and never come back that is...)
That said, I'm of the position of a wortcunner, as plants have spirits and require you to ally yourself and communicate with the spirit of the plant to properly utilize their power, as well as the correct planetary correspondences.
I personally have made and used Flying Ointments, and these are made using those aforementioned dangerous herbs. Things like nightshade, which does kill people.
There is very safe, lite version available from Sarah Lawless. She also has incense that is good for trance.
As for common non-entheogenic herbs, Saturnian herbs are useful, due to their connection with the chthonic otherworld and spirits.
Wormwood is a prime example. Absinthe is an alcohol I find good for achieving hedge-crossing with, and the wormwood spirit plays part in this.
Mugwort tea or incense is also a good example that works.