You didn't say if it was sun/shade. I'm guessing sun (??) from the plants mentioned.

I would strongly suggest visiting Prairie Moon's website. Their website is excellent and so is their print catalog which you can request to be mailed or view it online. The flowers and beautiful plants abound for all types of conditions, which are noted in their catalog/website. Everything from butterfly weed, to echinaceas, asters, goldenrod, lupins, baptisia, silene, silphium, monarda, and so many more. Check out some of the butterfly collections of seeds/plants Prairie Moon offers for a ready-made list of "pretty" plant suggestions.

I'm not a big fan of ornamental grasses in landscaping so I'm not the best one to ask but I'm sure there are much better choices than miscanthus. It is invasive in some locations. There are beautiful native grasses. I love the looks of the blue stems. The turkey-foot like seed head of the big blue stem is very cool. The picture below I took a local state historic site that has a native grass/forb restoration project in the works. This is big blue stem:

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You can see more native grasses and blooming plants in this restoration project here. They are all very pretty.

I suspect if you learn a little more about native plants, you'll find that there are many that will work wonderfully in your design.

FataMorgana

Here is a link that might be useful: Prairie Moon

I agree with the above. Sounds like access to native species is more of an issue than having attractive natives to choose from.

You might consider replacing the Nandina with Oak-leaved Hydrangea or Fothergilla major, both of which are more attractive and do not require regular pruning. Itea virginica is another nice small shrub. There are also compact cultivars of Viburnum trilobum that have excellent fall color. Here are some pics of some that I have grown:

Fothergilla major

Hydrangea quercifolia

Thanks for suggesting the Little Blue Stem. I went to two local nurseries today and they did NOT have any bluestems left but both recommended it. As long as I can get them, I'm going to replace a few of the calamagrostis with these.

I'm also going to replace the rest of the calamagrostis with Panicum 'Dallas Blue' or 'Northwind'.

The ONLY shrubs in the entire bed are the 3 nandinas. They are extremeley easy in my area and I have NEVER pruned mine in 15 years so I think they will work well. I also wanted at least some evergreen color in there. The others suggested will get either too big or too small for this spot.

I like spicebush, Lindera benzoin, as nice specimen plants. While generally an understory plant, they do survive quite nicely in sunny places. In my experience, they tend to be smaller and more compact/bush like in those locations. No pruning needed. If you get at least 1 male and 1 female plant, the female will have very attractive berries.

Elderberry, Sambucus spp., are nice. Flowers plus attractive berries.

Various viburnums are native and of varying sizes. Flowers, berries, etc.

Some dogwoods, Cornus spp., can be small and well behaved. Some like the red osier add winter interest.

I believe there are smaller witch hazel cultivars. Witch hazel is a beautiful bloomer when little else is.

Carolina allspice, Calycanthus floridus, is nice too.

FYI, the fothergilla suggested is a nice one! I will add that one to my own lawn and gardens soon. I already had or have added all the ones I mentioned above.

Stop by a local nursery. All of the locally owned nurseries here feature native plants - while the big-box stores have some I find their selection of native plants to be rather limited. Ask the nursery staff questions and work with them. I have always found the people at the locally owned nurseries to be far more knowledgeable and helpful.

FYI - lavender is a short-lived perennial. I would avoid it in any planting that is not going to be tended. There are longer lived plants, like monarda (aka bee balm), that bloom in a similar color palette, are native, and need no care once established.

FataMorgana

For a dry sunny spot you have to take a serious look at Wild Blue Indigo, Baptisia australis, which is very shrub-like in appearance.

Butterfly weed, Asclepias tuberosa is a top butterfly magnet.

Prairie Dropseed, Sporobolus heterolepis, is a short elegant prairie grass which is especially nice when used as a border plant spaced 24 inches apart.