More Advice On Backyard, Deadly Plants
When my son was young, about 4th grade, he was playing in the field with friends. The field was bordered by oleander. My son told the others that it was poisonous and not to touch it. One of the boys promptly ate a leaf! I was freaking out and immediately called poison control. The man I spoke with said that the boy would have to eat several leaves before it would affect him. Boy was I relieved!
Lily of the valley is famous if you watch AMC. Walter White uses it to poison a kid in Breaking Bad.