Полли из Молли, а Молли из Мэри :)
Дэйзи - это маргаритка по-французски, насколько я понимаю.
Вот что ещё пишут:

I believe Margaret, Meg, or Meggie changing to Peg or Peggy/Peggie is due to old variations between English and Scottish pronunciation of names that start with "Ma" in English becoming "Pa" or "Pe" names in Scotland a few hundred years ago. It happened to a few other "Ma" names too, for example, Mary or Molly to Polly, Martha or Mattie to Pattie or Patsie, and (I've only seen this once) Matthew or Matt to Pat.