Here is an alphabetical list of common house and garden plants that are poisonous and/or hazardous to young children. This is not a complete list and you should contact your local poison control centre if you have any question regarding other plants.
apple tree
autumn crocus
azalea
belladonna lily
bleeding heart
buttercups
cherry tree
christmas rose
chrysanthemum
clematis
daffodil
dieffenbachia
elderberry
elephant's ear
English holly
English ivy
fig tree
horse chestnut tree
hyacinth
hydrangea
iris
lily of the valley
milkweed
mistletoe
morning glory
narcissus
nightshade
oleander
peach tree
philodendron
poinsettia
poison hemlock
poison ivy
poison oak
potato (eyes, stems, spoiled parts)
rhododendron
rhubarb leaves
strawberry bush
sweetpea
tobacco
tomato leaves
wild mushrooms (all wild mushrooms, fungi and toadstools should be considered toxic until known to be otherwise)