I was also looking for boxer briefs and couldn't find them so I just went with boxers (on the poll, not in the store). Boxer briefs are the greatest innovation in men's underwear since the "commando" option.
In case someone downvoted you because they don't know what they are:
Boxer briefs are like boxers, only tighter and more elastic-y. Advantages over boxers include:
you can put your pants on without having to pull your underwear back down around your legs
if you're wearing shorts, the wind won't blow up them and freeze you
they don't have that big open hole in the front that makes it embarrassing to take your pants off when the doctor is trying to look at your leg
my wife likes them better
The last reason is why I started wearing them in the first place. They were a Christmas gift from my wife, and I liked them so much that I bought more. It's not like guys have that many underwear options, so it's nice to find something new that actually works.
At first I was a little bewildered as to what to choose, but I recently bought some "boxer briefs" that were labeled "trunks" so that's what I chose. I think they are the same thing, but I don't really keep up with underwear terms..