Introducing yourself to the new neighbors is one of those rare times popping in unannounced is good manners. Feel free to approach neighbors while they are outside in their yard or wrap on their door and introduce yourself. Such meetings should be brief. The goal is an introduction and maybe an exchange of telephone numbers or emails.
Is it necessary to bring a gift?
Welcoming new neighbors to the neighborhood is a thoughtful gesture and needn’t be expensive. A bouquet of flowers, homemade cookies or even a local telephone book are great ideas to make someone feel welcome. If you learn of a neighbor’s arrival after several weeks, months, etc. and they are clearly settled in, do introduce yourself, but a gift is not really necessary.
(sourced from Ettiquette by Peggy Post)