daffodils are poisonous I think. Not sure how they affect dogs though? The bulbs are the most dangerous part.
EDIT
http://www.provet.co.uk/petfacts/hea...lpoisoning.htm
Dogs can be indiscriminate eaters, and are often seen eating grass and garden plants. Whilst most plants are not toxic some, such as the Daffodil, can be lethal.
All parts of the daffodil plant (Narcissus poeticus) which is a member of the lily family (Amaryllidaceae) are toxic - especially the bulb. If a dog eats or chews the bulbs, leaves or the flowers it can develop signs of poisoning, including :
Diarrhoea
Vomiting
Staggering
Collapse
Unconsciousness
Coma
Death in a few hours
The most serious signs are only seen if the dog has eaten a large amount but the LD50 (dose at which 50% of animals will die) for dogs is 15g of Daffodil bulbs ...which is not a lot.
The toxins contained in Daffodils are alkaloids including galanthamine and lycorine and there is no specific antidote.