Yes, I speak American English and I've never heard "needful" being used. But Robert's answer, meaning "full of need" (therefore "needy", different than "necessary") makes sense. ex. For someone who is needy, it is necessary to receive lots of love and affection. (here, I used "needy" in the sense of a relationship, not money)

"Needful" is very uncommon in Western English (US, Britain, Australia, etc.). I believe that it's used in India more often. It can mean the same thing as necessary, or it can mean "needy" as someone who needs money.