Mail Order Natives in FL seems to have a very high percentage of good reviews on Garden Watchdog. I’ve linked the page for native azaleas and their selections, but they carry a good variety of other plants.

http://www.mailordernatives.com/rhododendrons-native-azaleas/

https://davesgarden.com/products/gwd/c/528/

Classic Viburnums can help you find Viburnums that suit your growing conditions and are natives. I have heard only positive reviews from several gardeners about this company. Though they aren’t in your part of the world, they are about the best source for Viburnums, native or not, and there are native Viburnums in your area.

http://www.classicviburnums.com/index.cfm/fuseaction/home.showpage/pageID/24/index.htm
https://davesgarden.com/products/gwd/c/5988/

Lazy K Nursery is in GA and has a good reputation on Garden Watchdog. They specialize in native Rhododendrons and Azaleas and their cultivars, but also have some other trees and shrubs and perennials.
http://www.lazyknursery.com/LazyKNursery_OrderForm2008.pdf

https://davesgarden.com/products/gwd/c/1177/

Woodlanders carries a mix of native and exotics and I know of several gardeners that have been happy with their selections. I did a search for US to get the native plants on their list. They pretty consistently give the source of plants in their catalog.

https://www.woodlanders.net/index.cfm

https://davesgarden.com/products/gwd/c/315/

Plant Delights Nursery is in Raleigh, NC, so more coastal, but sells a mix of native and exotic perennials. Their info gives country or region of origin. You might want to take a field trip there at some point since shipping can be high, but they have a demonstration garden that friends tell me is very nice.

https://www.plantdelights.com/
https://davesgarden.com/products/gwd/c/9/

You can also ask for suggestions on various other Houzz gardening forums specific to your area:

Southern gardening

Carolina gardening

or the forum that deals with Natives, though not necessarily to your part of the US
Gardening with Natives

Beth, the suggestion to explore Woodlanders for your specific plant needs is excellent. I am very familiar with this nursery. The propagator is one of the best in the country. If possible you should visit the nursery which is in Aiken, SC. There you will find few attractive displays to tempt your wallet. Just a hardworking, helpful nursery operation which sells many plants native to the Carolina's.