I have ferns growing in my woods near a wetland that get very tall, about 4 feet high. They are big. Unfortunately I don't know what kind they are only that they grow wild here in Wisconsin. Whether or not they'd be black walnut resistant, I can't say...

Found this by simply Googling Juglone Resistant Plants...

Plants Observed Growing Under or Near Black Walnut*

Japanese Maples, Acer palmatum and its cultivars
Southern Catalpa, Catalpa bignonioides
Eastern Redbud, Cercis canadensis
Canadian Hemlock, Tsuga canadensis
Vines and Shrubs
Clematis 'Red Cardinal'
February Daphne, Daphne mezereum
Euonymus species
Weeping Forsythia, Forsythia suspensa
Rose of Sharon, Hibiscus syriacus
Tartarian Honeysuckle, Lonicera tatarica, and most other Lonicera species
Virginia Creeper, Parthenocissus quinquefolia
** Pinxterbloom, Rhododendron periclymenoides
**'Gibraltar' and 'Balzac', Rhododendron Exbury hybrids
Multiflora Rose, Rosa multiflora
Black Raspberry, Rubus occidentalis
Arborvitaes, Thuja species
** Koreanspice Viburnum, Viburnum carlesii, and most other Viburnum species

Pot-marigold, Calendula officinalis 'Nonstop'
Begonia, fibrous cultivars
Morning Glory, Ipomoea 'Heavenly Blue'
Pansy Viola
Zinnia species
Vegetables
Squashes, Melons, Beans, Carrots, Corn
Fruit Trees
Peach, Nectarine, Cherry, Plum
Prunus species Pear-Pyrus species
Herbaceous Perennials
Bugleweed, Ajuga reptans
Hollyhock, Alcea rosea
American Wood Anemone, Anemone quinquefolia
Jack-in-the-Pulpit, Arisaema triphyllum
European Wild Ginger, Asarum europaeum
Astilbe species
Bellflower, Campanula latifolia
**Chrysanthemum species (some)
Glory-of-the-Snow, Chionodoxa luciliae
Spring Beauty, Claytonia virginica
Crocus species
Dutchman's Breeches, Dicentra cucullaria
Leopard's-Bane, Doronicum species
Crested Wood Fern, Dryopteris cristata
Spanish Bluebell, Endymion hispanicus
Winter Aconite, Eranthis hyemalis
Snowdrop, Galanthus nivalis
Sweet Woodruff, Galium odoratum
Herb Robert, Geranium robertianum
Cranesbill, Geranium sanguineum
Grasses (most) Gramineae family
Jerusalem Artichoke, Helianthus tuberosus
Common Daylily, Hemerocallis 'Pluie de Feu'
Coral Bells, Heuchera x brizoides
Orange Hawkweed, Hieracium aurantiacum
Plantain-lily, Hosta fortunei 'Glauca'
Hosta lancifolia
Hosta marginata
Hosta undulata 'Variegata'
Common Hyacinth, Hyacinthus Orientalis 'City of Haarlem'
Virginia Waterleaf, Hydrophyllum virginianum
Siberian Iris, Iris sibirica
Balm, Monarda didyma
Wild Bergamot, M. fistulosa
Grape Hyacinth, Muscari botryoides
Sweet Cicely, Myrrhis odorata 'Yellow Cheerfulness,' 'Geranium,' 'Tete a Tete,' 'Sundial,' and 'February Gold'
Sundrops, Oenothera fruticosa
Senstitive Fern, Onoclea sensibilis
Cinnamon Fern, Osmunda cinnamomea
Peony, **Paeonia species (some)
Summer Phlox, Phlox paniculata
Mayapple, Podophyllum peltatum
Jacob's-Ladder, Polemonium reptans
Great Solomon's-Seal, Polygonatum commutatum
Polyanthus Primrose, Primula x polyantha
Lungwort, Pulmonaria species
Bloodroot, Sanguinaria canadensis
Siberian Squill, Scilla sibirica
Goldmoss Stonecrop, Sedum acre
Showy Sedum, Sedum spectabile
Lamb's-Ear, Stachys byzantina
Spiderwort, Tradescantia virginiana
Nodding Trillium, Trillium cernuum
White Wake-Robin, Trillium grandiflorum
Tulipa Darwin 'White Valcano' and 'Cum Laude,' Parrot 'Blue Parrot,' Greigii 'Toronto'
Big Merrybells, Uvularia grandiflora
Canada Violet, Viola canadensis
Horned Violet, Viola cornuta
Woolly Blue Violet, Viola sororia
*These are based upon observations and not from clinical tests.
**Cultivars of some species may do poorly.

Ostrich ferns aren't bothered by black walnuts either. Once established, the ostrich ferns can grow quite large. Mine have adapted to full sun and are huge - almost prehistoric looking.

I find Choisya ternata, Clerodendron bungei, Eleagnus pungens, Pollia japonica, Heptacodium miconioides, and Magnolia grandiflora do well under/near a black walnut.

Your backyard sounds very similar to mine.
I've got Viburnum Trilobum & Arrowood growing well, but in that level of shade they aren't blooming so no berries.
Spicebush/Lindera is doing wonderful - yellow fall color, yellow flowers very early spring, & red berries in winter. Grows fast to 6' tall in moist areas so a mail order plant is an option if you can't find locally.
Carolina Allspice is also growing great. Unusual brown flowers that smell nice. 4'h x 4'w
Itea is doing good in shade - the fall color is better w/ more sun, but it's got a nice arching shape, flowers & holds onto it's leaves most of the winter. But they leaf out very late in the spring so I prefer to have another plant behind it. 3'h x 4'w
I moved a variagated Dogwood out of full sun into this shady area temporarily, but it's growing like crazy so I'm going to leave it.
I just bought a small Canadian Hemlock which I'm sure will do good here.
In a slightly bright spot I planted Arborvitae Brabant (reportedly more shade tolerant) for privacy, but they lost alot of density quickly, so I bought more, moved then closer & replanted in a zig-zag.
Bladdernut was doing good (6'h x 4'w) until the dogs urinated it to death.
Pumilla Dogwood is in a wet spot & looking very healthy. It doesn't bloom in the shade, but the leaves are thick & green, w/ red at the edges. I like it alot.
I tried Pieris - it died quickly.
Kerria is very thin, but good up against a fence.
Viburnum Sargentii looks awful - not sure if it's a shade or walnut issue.