The day after Andrew passed away, my mom was in the garden working. She saw a beautiful dragonfly land beside her and she knew immediately that it was a sign from Andrew.
Here are some facts about dragonflies:
1. Dragonflies have been around since before dinosaurs existed.
2. Dragonflies are one of the only insects who have teeth.
3. They are often seen as symbols of immortality, regeneration. In Native American legend they are the spirits of the dead watching over their loved ones.

Some more interesting info:

Breaks illusions..
Brings visions of power,
No need to prove it,
Now is the hour!
Know it, believe it,
Great Spirit intercedes,
Feeding you, blessing you,
Filling all your needs.

-From a Navajo medicine card about dragonflies.

It is said that people who have the dragonfly as their totem have had emotional and passionate early years, but as they get older they balance their emotions with mental clarity and control. The dragonfly symbolizes the process of going beyond limiting self-created illusions toward a mature sense of self. (Taken from Jung Talk-Dragonfly)

For some information regarding dragonfly mythology, please visit:
Cultural Odonatology