Hi, 

How shaded is the area? Are deer in issue? A native viburnum could work for a few of the requirements but the 'fragrant blooms' may lean towards the unappealing side of fragrance. Native Viburnum can be rather strong smelling and most people would say they are quite stinky (rotten fish, wet dog etc). Viburnum are showing that they are compatible with Black Walnut trees though. The only ones that are semi-evergreen are Viburnum x. rhytidophyllum and Viburnum x. pragense and they are both non native but to our knowledge not invasive. 

One thought for screening and to give you seasonal interest - if there is enough sun - is a Panicum switch grass in the back ground and then maybe a few Ilex verticillata, Winterberry Holly in the foreground. The winterberry will lose its leaves but the berries should remain for most of the winter. Winter berry need a male pollinator so you have to match the female fruiting shrubs with the male species to have them set fruit. You can tuck the male into the back garden somewhere, as long as it is within approximately 100 foot vicinity (not a proven distance but just as long as it is close enough for the pollinators to travel to different plants).

Another plant that gets attractive red berries that persist in the winter is Aronia arbutifolia Red Chokeberry. It also has white lightly fragrant blooms in spring and nice bright red fall color. It can withstand wet soil and part shade. You can use cuttings from these for winter greenery.

Maybe a witch hazel could work for you, Hamamelis virginiana. It won't be evergreen but will have interesting blooms when not many other things will. 

In terms of a plant that you can cut for winter greenery, there aren't many that we can think of that will withstand the prolonged wet feet in the spring. Perhaps a Dwarf Atlantic White Cedar if you could find one, would work for you. 

Not an evergreen but red twig or yellow twig dogwood would probably prefer the wetter soils and you can you branches of those in winter greenery arrangements. 

We can share some plant lists of juglone tolerance and susceptibility that you can cross reference with the plants we suggested, but this is a horticulture topic with little conclusive evidence regarding the real-world risk of juglone to plant health (compared to lab experiments). You can learn more about one main counter-argument to juglone toxicity in the Washington State University publication: “Do Black Walnut Trees Have Allelopathic Effects on Other Plants?” Juglone-resistant plant lists may differ somewhat or be incomplete for this reason -- observed vulnerabilities may not be consistent because of interference from soil microbes, underlying plant health prior to exposure, and other environmental conditions. 

• Landscaping and Gardening Around Walnuts and Other Juglone Producing Plants – Penn State

• Black Walnut Toxicity – Wisconsin Extension

• Nature's Herbicides and Lessons from Black Walnut Trees – Cornell blog

• Black Walnut Toxicity – Morton Arboretum

Let us know if you have any questions with the information provided or plant recommendations. 

Emily