After doing the thread on Booby Traps, I decided to look up May Apples. This is one thing that – unlike “Poison Parsnips” – I do rememmber from my Boy Scout days. May apples grew in great numbers at my Scout camp. The fruits weren’t as small as on the pictures on the internet, they were freakin’ Huge!:
http://www2.foodtv.com/terms/tt-r2/0,4474,3979,00.html
http://www.briartech.com/earlyspring/mayapple/may.htm
http://www.motherearthnews.com/top_articles/1977_July_August/Behold_the_Mighty_May_Apple
The thing is, the fruit is only edible at certain times. Unripe fruit (like the roots, leaves and stems at all times) is not merely poisonous, but highly toxic. And nobody seemed to know exactly when they were ripe, so we left them alone (although eating other edible plants in the vicinity). Even when ripe, there’s apparently still a risk, at leasty to some peopler. Yet others use this plant to make preserves!
http://www.ces.ncsu.edu/depts/hort/consumer/poison/Podoppe.htm
We apparently have here “American Vegetable Fugu” – a food that will, if improperly prepared or not completely separated from the rest of the item, kill you. Is it really worth the risk?
Anybody ever eat these?
I grew up n N.E. Ohio and used to run the woods frequently. We ate may apples, they were a bit bigger than a ping pong ball and yellowish when ripe. They grew on a small plant w/ large leaves. I never knew they were supposed to be poisonous, don’t recall ever having any problems.
There was some research about using them to kill off skin cancers, but I never heard the results. Thepreliminary data was that the at least help shrink the cancers.
I believe May Apples were less toxic when the leaves yellowed, that being when the plant withdrew the poison back into the roots for next year. They become less toxic at that point from what I read. They however still cause problems when eaten in more than small amounts. I would never trust the sources I read enough to eat one. I would only try it if a reputable source did a study on it, and they ate it first.
Some foods are worthless or dangerous unless prepared in a certain way. I don’t know what the poison in May Apples is, but it may be diminished by cooking. I think that it may be an oxilic acid, which I believe is unaffected by heat.
I’ve always loved those plants. I never knew you could eat the fruit, but I always loved taking frequent walks in springs to watch the leaves unfurl and spread out. I might have to try a May Apple this year (a small amount). According to the cites above they should be edible in a month or two. 
Just be careful and read the cites I’ve printed. I’d hate to be responsible, even in an indirect way, for contributing to the degradation of the well-being of a fellow Doper.
A small amount at the wrong time can be deadly.
I have them all over the place and never thought of eatting them.
I don’t believe the leaves of mine are mottled, though. They come up with the
trillium in the Spring.
I have a list of Dopers and non-Dopers I’d be happy to send some to. 
Please note:
http://foragingpictures.com/plants/May-apple/
I’m assuming the guy shown eating the plant isn’t dead. Please be careful if you decide to sample these.
And this:
Talk about your mixed messages!
So be careful out there.
http://www.ces.ncsu.edu/depts/hort/consumer/poison/Podoppe.htm
Mine look like that.
Get your orders in now!
(Please pay before shipping.)
Don’t worry, before I posted I looked at all the cites you listed. I wouldn’t eat it unless I was sure it was ripe. Thanks for the concern.
I’ll worn family members before-hand though just in case. They will track you down and make you pay if I die! 
I couldn’t get the earlier links to open on this old computer, but CalMeacham’s site worked. Those look the same as the ones we used to eat as kids. I don’t recall the lemon flavor, as I remember the skin was fairly thick, w/ seeds inside similar to a bell pepper (only much smaller). They were mildly sweet, but a bit bland. Being kids, I’m sure we bit into green ones and spit them out if they weren’t ripe yet.
I couldn’t get the earlier links to open on this old computer, but CalMeacham’s site worked. Those look the same as the ones we used to eat as kids. I don’t recall the lemon flavor, as I remember the skin was fairly thick, w/ seeds inside similar to a bell pepper (only much smaller). They were mildly sweet, but a bit bland. Being kids, I’m sure we bit into green ones and spit them out if they weren’t ripe yet.