We are surrounded by poisonous plants.
There's a whole list here:
http://www.rhs.org.uk/advice/profiles0606/Take CareBeAware.pdf
Aconitum is particularly poisonous but so is laburnum , yew, foxgloves of course and many others. Rhubard leaves are full of Oxalates which are poisonous.
I have monks hood in the garden, the children know it's poisonous it's not a problem.
Monkshood seems to have gathered a bit of a mystique about it - I wonder if it's been exagerated in TV dramas - I've heard people claim you can be poisoned by touching it but the RHS just class it as irritant to the skin - personally I've never found it as such maybe in higher exposure.
I think the last person I heard die of from accidental self-poisoning was some years ago when an older man with liver disease mistook wild narcissus bulbs for wild garlic.
It's a matter of keeping things in perspective. There's a nice little article on posonous plants on the BBC web page here:
http://www.bbc.co.uk/health/conditions/poisono usplants1.shtml