We have one of the best zoos in the world, that take horticulture very serious.
Home | Omaha's Henry Doorly Zoo
I would recommend getting plugged into one of the state associations to network... here are a couple:
Nebraska Nursery and Landscape Association
UNL | Extension Horticulture
Follow-up with the Arbor Day Foundation, they are headquartered in Nebraska (1/2 way between Omaha and Lincoln):
Trees - Arbor Day Foundation
Not sure if you like turf work, but this area probably has the highest ratio of golf courses to people...
Nebraska Golf Association
There are also some large landscaping companies that have horticulturists due to the seriouseness of that business around here.
http://www.buildingtradesdir.com/gui...landscape.html
Previous recommendation for Lauritzen was excellent - here is their site:
https://www.omahabotanicalgardens.org/