I've seen article about great benefits of eating avocado seeds. And another here.  Does it mean avocado seeds are edible? How do you eat it then?  On Wikipedia page we can read:     Avocado leaves, bark, skin, or pit are documented to be harmful to animals; cats, dogs, cattle, goats, rabbits, rats, guinea pigs, birds, fish, and horses can be severely harmed or even killed when they consume them.   How about humans?  Somebody from here suggested that the avocado pit is mildly toxic.  
Persin is a fungicidal toxin present in the avocado which is generally harmless to humans. However when consumed by domestic animals in large quantities it is dangerous.  It is an oil-soluble compound structurally similar to a fatty acid, and it leaches into the body of the fruit from the pits. Negative effects in humans seem to be primarily in allergic individuals. 