In Buddhism Can Devas do Something For Us?

My mother is a christian woman but has strong traditional roots in voodooism and ancestral worship.My question is,Is it possible for human beings to invoke a deva/gods/territorial spirits(nagas etc) to do our bidding? In a Buddhist context Can a Deva help a human being? Is there such a story in the suttas.Why would a Deva help a human being? According to my mother a particular deva helps us because he was our family/relative/ancestor.Is this compatible with Buddhist Beliefs?