Button, button, who's got the button?

My wife and I went antiquing this weekend. No, we didn't go around pelting the unsuspecting with flour.

I found lots of interesting pop culture items, only a few of which I could actually purchase.

Here are two buttons I got.

The one on the bottom was clearly a promotional item for Swanson, presumably their line of TV dinners.

But the NBT on NBC button, I have no idea. I'm sure someone out there has a clue. Let me know so I'm not up all night puzzling over it.