Pop sorghum is available from Native Seed/Search, last I knew. Sorghum is often called milo in the USA.
Although popsorghum does pop better and is better tasting than the regular milo grown for cattle feed, regular commercial hybrid milo can pop if dumped into hot oil.

I had a friend, now long moved away, who popped sesame before using it in stirfries. Some pop amaranth, or say they do. I haven't seen it popped.
Walter

Lots of grains (wheat, barley, corn, etc) and pseudograins (amaranth, quinoa, buckwheat, etc) can be popped. They're tasty!

There is also a bean native to equatorial regions of SOuth America called a Nuna bean. there's a ~ over the u.

They are photoperiodic and we were attempting to cross them in the early 90's to overcome the photoperiodic effect and long growing season required (we grew them in winter under lights).

I went on to another university and that Professor retired. Now others have sucessfully overcome the short day requirements but it is mired in patent issues. (See link for info and picture)

They are beautiful beans with many different colored seeds. The beans do "pop" but it isnt as dramatic as corn.

Here is a link that might be useful: Nuna beans

Interesting... after hearing that Nunas were "under development" 10 years ago, I wondered what had happened to them. Unfortunately, it seems that the primary focus was on commerce, not the backyard gardener.

I think the chickpeas can pop . get some and try it . teosinte can be popped also .

Popping Sorghum is becoming quite popular. It is essentially hulless, gluten free, low in calories & fat! It is a great popcorn alternative for those suffering from Celiac, Crohn's, or Diverticulits (but of course always consult with your doctor about this).

I like it because even the un-popped kernels can be further toasted and eaten as a delicious treat!

Here is a link that might be useful: Popping Sorghum