Large amounts of lead in a child’s blood can cause brain damage, mental retardation, behavior problems, anemia, liver and kidney damage, hearing loss, hyperactivity, developmental delays, other physical and mental problems, and in extreme cases, death.

could grind it up and blow a powder into the bedroom every night

Poison Hemlock All parts Fatal. Resembles a large wild carrot.

cooked like a carrot? or raw “carrot” with dip?

dunno if this would work….
bleeding heart has been fatal in cattle
If you fed someone a steak from a poisoned cow….

hyacinth, daffodil or narcissus bulbs may be fatal - perhaps slice and sautee them so they look like onions?

http://aggie-horticulture.tamu.edu/plantanswers/publications/poison/poison.html