Although the prickly pear cactus grows in all fifty states of the United States, I believe that only in the Southwest does it bring forth an edible fruit. In Spanish, that fruit is called Tuna. It is full of seeds which are easy to spit out, and is not excessively sweet the way some fruits are. In Mexico, it is cheap and readily available. I remember once in the 1980s buying a whole bag for fifty cents, more than I could finish in a month.If you ever visit the Southwest, you should give it a try, as it is not only tasty but incredibly nutritious.
But if you go to Mexico, be careful about ordering a tuna sandwich. The word for tuna (the fish) in Spanish is atun.