They are about as big as a thimble, the eggs are pea sized, you wont find the nest in the trees, yu will find them in bushes or shrubs, closer to the ground, they have a wonderful website hummingbirds.net
What Do Humming Birds' Nests Look Like?
The nest oh humming bird is made of saliva secreted by them in order to make nest. They secrete sticky saliva in the form of fine threads and make net of it. After exposure to air these saliva threads become hard so proving a place to live and lay eggs.