Here is a list of things that I have been told help labor start. People like to share these things with me now that I'm past due. I'll leave it up to you to figure out which ones are good ideas and which ones are probably unsafe. You can make guesses or add new ones in the comments.
-drinking castor oil
-having lots of sex
-taking evening primrose oil
-taking borage oil
-eating spicy foods
-taking long walks
-driving on roads with lots of potholes
-massaging the pressure point in your hand
-hooking up to a breast pump
I will say that out of these, I've done five; one Cathy says could make your placenta rupture from the uterine wall; and one of them made for an awkward conversation in line at Walmart.
Oh, and so far, none of them are working.