I know the bulbs are very poisonous to people due to alkaloid toxins, but not sure about the flowers? Most flower bulbs are toxic to humans but probably not to deer.
I had a shooting friend who went into a toxic coma due to this. He used to get fish and chips with a pickled onion every friday night after work. Just after Christmas one year he collapsed in a toxic coma late one friday evening. Turns out his normal pickled onion was actually a pickled Daffodill bulb which had been harvested by mistake!
Me and a couple of friends tried talking to him about shooting etc to try and bring him out but to no avail.
They eventually tried a new technique pioneered by the Dutch. He was placed in a warm room by a big window where he got loads of natural sunlight. Thankfully he came out in the spring.