No term that would confuse with the NCAA or a reminder of big city blight.
Agree, too much Big, and numbers. Just about all directions have been used, and this group is spread out. America, National, etc., too over-stating or redundant. No Trans, continental stuff. Too unsettling.
All those locales have pine trees, don't they? Tall Pines Conference?
Shady Oaks?; opps, sounds too much like a nuring home. Doubt can use rivers, lakes, and other bodies of water. White-tail deer are near all those places. Too many schools use bald eagle.
"Waves of Grain Conference" sounds too much like Kansas, Nebraska, and Iowa. "Blue Skies" may get confused with "Big Sky".
Stanford, used a tree for their political correctness re-naming.
Maybe after an early explorer that visited all those locations. DeSoto didn't; & there's already a Lewis & Clark College & L&C was all westward anyway.
Maybe name it after a person? Some President or a great educator? Hard to do also. Heck, find a great, benevolent philanthropist, who'll render major bucks for it to be named after him/her?
Maybe try a corporation sponsor-- like chicken sandwiches, tires, cameras, weedeaters, chips, apparel, etc. It happened to bowls.