I'm guessing that guy/gal was growing Pineapple Guave. It's not a true guava, but taste about like the name suggest. They produce a pretty flower in the spring that's edible. Fruits late summer. The scientific name is Feijoa sellowiana. These will actually do pretty well there in Dallas. They need a good bit of sun to thrive, but otherwise, you can hedge them, prune them, whatever. Easy breezy. I've found them at Lowe's on occasion.
Feijoa - Wikipedia, the free encyclopedia
P.S. Both my father and I have plenty of these in our garden.