I don't see your location on your profile but you mentioned some southern plants.. Are you int the south? How much land do you have/use? How did you get started?
Huh, weird, I've had my location up since I first joined...maybe something to do with the beta view on the site currently? Can other people see it? Anyway, I live near Columbus, Texas, USA (Colorado County). Zone 8b, verging on Zone 9. Humid subtropical, drought prone. Gulf coastal prairie ecoregion, more or less, although there's something of a confluence of different ecoregions in my area.
I hit the jackpot in that we have family land, about 550 acres. It is currently dedicated to
cattle ranching (not by my choice) and there were some gravel pits dug out in the '50s which fill from creek runoff and river flooding and provide habitat for lots of tasty fish, reptiles, and amphibians (white perch, bass, catfish, turtles, bullfrogs, mainly), plus waterfowl. I use pretty much all the land to spread out my impacts when hunting and wild harvesting. That being said, I could probably provide all/the vast majority of my diet from about an acre of intensively cultivated land using only native species, but they'd have to be "gardened" and not just wild harvested.
When I lived in Austin, TX, I provided a smaller portion of my diet in this manner, but most of the food sources I mentioned were still available and there was little competition for them; for instance, pecans, not to mention acorns, rotted on the ground, and weeds are present anywhere. I liked to harvest them from people's plots at the organic community garden near me, since I could be sure that they weren't sprayed with weird 'cides and the gardeners were happy about it (I always asked permission, of course). Fruit crops and animal protein were harder to come by, but not impossible. I didn't trust the water to fish in. I trapped some squirrels while I was there, but I didn't have a good understanding of how animal populations worked there and was reluctant to kill many. In some ways they seemed like overpopulated pests, but it also seemed that the places they were present were mostly refugia into which they had been forced and so I mostly just left them alone. It always frustrated me that they'd plant crepe myrtles by the thousands, or decorative natives, but no one would plant any of our native fruit trees in the parks, campuses, or other areas. I can understand avoiding fruit trees where they might drop fruit on cars or sidewalks, but you'd think that parks, woody areas, and neglected areas would have been just fine, but no.
I also forgot to mention in my last post a major food plant for me, which is prickly pear cactus. The fruits are good to eat and for jams, syrups, and wines, and the pads are the most substantial wild vegetable I harvest (makes a nice change from just leafy stuff) and are really tasty when cooked up. They were also available in Austin although not as easily.
In more arid areas of Texas, leguminous trees such as mesquite were a major staple, but they don't really grow in my particular area that I know of.
I was also lucky in that I had older parents, and my dad and his family had been in this area for a long time, so there were strong traditions of eating and preparing native food and game. Dad was a really good hunter and fisherman, one of the best around. I'm nowhere near his level, but I can fend for myself pretty well. These foods were prized--a good snap sausage recipe or duck and dressing or gumbo or a way of making dewberry pie or Mustang jelly or wine is something people still take seriously here, and getting to go hunting, fishing, or frog gigging with older relatives/friends was a big deal when I was little. Showing younger kids when we were camping out how to fillet a fish and wrap and bury it under coals, or singe the tiny thorns from prickly pears was fun and made us feel good. So I had a head start to some degree. I have delved deeper into the less valued food plants (mostly the weeds) as I've gotten older and more into this sort of thing, by reading books, websites, forums like this one, etc. I also make it a point to talk to older people in town, borrow their old cookbooks and family recipe files, and ask everybody I know about local foods and how they prepare them.
If you're interested, I keep a list of Texas native plants that I eat and otherwise use on Google Docs. It's a work in progress, not comprehensive, but it may give you some idea of how I subsist, and of course many of the plants aren't limited to Texas:
https://docs.google.com/spreadsheets/d/1ACVDAL7mY2-HFn1HPqlO-Dmn7m1YtJ0mRL2dmAJmU-o/edit?usp=sharing