Lily of the Valley
Angel's Trumpet is one of the plants with drooping white bell shaped flowers. Lily of the Valley is another plant with white drooping bell shaped flowers.
It is called a Gong
The "cloche" was a popular bell-shaped hat in the 1920's. Cloche is also French for bell
cloche hat
A calla is actually a flower like herb with a bell shaped leaf that is nearly always mistaken for the plant's flower. The calla's flowers are actually the small blossoms inside the bell shaped leaf. Calla lilies are one of the most popular types of calla. The calla lily has a bell shaped leaf that is about 7-10 inches long that presents in a variety of vibrant colors. This understandably leads to the mis-perception of its actually being the flower.
The dogbane is a North American plant which has bell-shaped white and pink flowers. Plants with bell-shaped flowers are from the genus Apocynum.
umbrella
It is called a normal distribution.
Abelia
No. They are symmetrical and bell-shaped.
The Lily of the Valley is a woodland plant with large broad green leaves and small white bell shaped sweetly scented flowers. A full description and photo is available by clicking the related link.