Produced by Jelly Belly, the gourmet jelly bean manufacturer.

Sugar, Corn Syrup, Modified Food Starch. Contains 2% or less of the following: Natural and Artificial Flavor, Color Added, Yellow 5, Salt, Beeswax, Carnauba Wax, Confectioner's Glaze.
Manufactured in a plant that processes peanuts.

The buttered popcorn jelly bean is white, speckled with a bright yellow color. Its initial flavor is in fact very similar to buttered popcorn -- salty, buttery, with a slight corn flavor. However, being a jelly bean, it is much sweeter than popcorn.

Many people are shocked, amused, or incredulous when they discover that such a bizarrely flavored jelly bean actually exists. Many people are afraid to try it, and of those who do, many don't like them at all.

I myself like them, although I couldn't eat more than a small handful at one time (unlike the real thing). I have found that most people who do like the buttered popcorn flavor like it a lot -- in fact, many of them cite it as their favorite jelly bean. From Jelly Belly's own promotional material:

Surprising popcorn flavor just like you get at the movies. Leave it to the candy makers at Jelly Belly to get a flavor like that into a jelly bean. You either love it or hate it. And those who LOVE it have made it the number one most popular flavor of all. Even Orville was a fan.