Things I'd be aware of:
- Most places in the Ozarks the soil is thin and ancient, stony, without a lot of nutrients or organic matter. Soils will be deeper on ridgetops (and really, the Ozarks aren't "mountains" but a couple plateaus deeply dissected by rivers and streams), and in those stream bottoms. Soils are also generally deeper on the northern and eastern borders (the counties bordering the Missouri and Mississippi rivers). There's a considerable amount of exurban development, but some nice smaller communities as well.
- Chicken houses are big business. Especially in the southwestern Ozarks, south of Springfield and west of Branson. You'll know by the smell. Check out aerial imagery on any property you're interested in and see if there are any in close proximity (I found this handy map: https://modnr.maps.arcgis.com/apps/webappviewer/index.html?id=cf630b020a17452fb30994cb4b36f003
- Feedlots aren't uncommon. Missouri's second only to Texas in beef production and feedlots are a feature of the landscape, typically mom-and-pop operations of <200 animals. Ozark streams are surprisingly high quality considering how often cows are pooping in them. Again, know your neighbors, drive around the neighborhood, scope out aerial photography.
- There's a legacy of mining (in places). Mostly around Joplin and south of St. Louis (Jefferson, Iron, Reynolds, and parts of Washington, Franklin, St. Francois, and surrounding counties). Mostly lead and zinc, some cadmium, and on some parcels in those parts of the state there may be heavy metal contamination. Parts of the region have underlying granitic bedrock and issues with radon, too.
- There isn't a lot of elevation, but there's a lot of relief. Environmental conditions (soil type, soil moisture, amount of sunlight, etc) will vary dramatically from a ridgetop to a creek bottom, over only a couple hundred meters. Air drainage is something to keep in mind, especially with fruit trees.
- Soils can be thin and rocky. They're ancient (untouched by sea level rise or glaciers for a couple million years), so a lot of the nutrients and organic matter have leached out over time. You can have seasonally perched water tables where there's an impermeable clay layer a few inches or a few feet below the surface. Community Commons is a free online mapping tool that where you can add all sorts of data layers- they have a "soils" option, and you can use it to explore soil properties of parcels you're interested in- it's communitycommons.org
Places to check out?
I-44 west and south of Springfield: Crane, Cassville, maybe Aurora.
Springfield to Lebanon (South of I-44): Mansfield, Forsyth, Ava.
Lebanon to Rolla (South of I-44): Hartville, Cabool, Willow Springs, Newburg, Licking
Lebanon to Rolla (North of I-44): Crocker, Dixon, St. Elizabeth, Vienna, Freeburg
Rolla to Sullivan (South of I-44): Mountain View, Thomasville, Alton, Winona
Rolla to Sullivan (North of I-44): Belle, Linn, Owensville
Sullivan to St. Louis (South of I-44): Centerville, Van Buren, Caledonia, Fredericktown, Marble Hill
There's also some fairly rugged portions of the state outside the Ozarks. The counties just north of the Missouri River between Columbia MO and St. Louis can be quite rugged, and about an hour north of St. Louis, near Mark Twain Reservoir, is pretty hilly as well. Land's more expensive up there, but it's a nice area and not too busy.