Daffodils were originally called affodills, which is a variation of the medieval Latin name for the flower, affodillus. Nobody can seem to account for how the “d” came to be added to the front of the word, except that perhaps it sounded too good to resist. It may have derived from a kind of lazy spoken contraction when the name is preceded by the word “and,” such as in this sentence: “In the field were many tulips and affodills.” What we now call “daffodils” are actually a flower that goes by the botanical name of narcissus. In Greek mythology, Narcissus was a beautiful youth who fell in love with his own reflection in the water. Not realizing it was his, he pined over himself to the point of death. The flower which bears his name is said to have sprung up where he died, and people who are self-centered are called narcissistic. The tale is in the Roman poet Ovid’s classic work, Metamorphoses.
The plural of the flower, incidentally, is narcissi. As for that early bloomer the crocus, both crocuses and croci are acceptable for the plural (but people will look at you funny if you say croci). Personally, I think the plural of daffodil should be daffodilli. It just sounds right.