Huckleberry, salal, ferns...look around and see what is toughing it out in dry rooty ground under nearby conifers. If cats have been in there it may not be good spot for kids to use, maybe have to excavate and replace surface soil first, then put down cobbles to discourage return visits.

I have a lot of dry shade areas under cedar trees and have found that periwinkle or sweetwoodruff do very well in these areas. Beware thought of lamium unless you never want to get rid of it.I was in a garden approx.2 acres that the whole understory was covered in lamium, looked quite pretty but a bit to much for me.Also the other plants suggested before me are also wonderful.

Periwinkle also makes patches in the woods, presumably at the expense of native plants.

That lamium was most likely lamiastrum, a related but highly aggressive spreader. I've grown lamium in dry shade for years and it is extremely well behaved - much more so than the Gallium (sweet woodruff) which has encroached everywhere in my garden or tries to if I am not dilligent in removing it.

There are a great many plants for our area that are suited for dry shade - in addition to the ones Ron mentions (and natives are an excellent place to start), you could try sarcococca (sweet box), Euphorbia robbiea, Geranium macrorrhizum, Iris foetidissima, various hellebores, epimediums, fatsia, aucuba....a pretty long list. Keep in mind that even those plants tolerant of dry shade need a little help to get established and may need the occasional watering even after establishment if no rain hits this area at all.

Lamiastrum = Lamium galeobdolon argentatum. "Only the clone 'Florentinum' = 'Variegatum' is a major weed" (Jacobson, WILD PLANTS OF GREATER SEATTLE).

"Junior naturalists" might have implied natives only.

I have a wonderful Daphne odora on the north side of my house with very sharp drainage. Pulmonarias might do well there too.

Aspidistra elatior or commonly known as Cast Iron Plant. Very hardy for dry shade. I have quite a few clumps of them in my garden. Also Fatsia japonica is another good one, but it can grow to a fair size. It always looks good, especially in shade. Joe

Sarcococca are incredibly fragrant and blooming now. Very tough dry shade plants. various cultivars.

Don't forget the low ground covering symphytums. Evergreen, though a bit ratty in winter, with nice yellow tube like flowers in spring. I've had good luck also with huckleberry, (evergreen and edible fruit--can get to 6-8'), Epimedium, periwinkle, Fatsia, Hellebores, Christmas fern (the native from our woods), Trout lily, Osmanthus, mahonia, iris reticulata, Sarcococca, vine maple, and geranium macrorhizzum. Good luck.

I have a native Mahonia in a dry, shady spot in my yard. Sarcococca is nice, too, as others have suggested.
I think Fatsias would be ugly, but that's just me.

Celandine Poppy (Stylophorum diphyllum )grows really well in my dry shade garden. The yellow flowers brighten up the beds and the foliage is interesting. Does reseed but not so invasively in dryer conditions.

I've posted this before, but as a visual reminded of how visciously invasive lamiastrum can be, here it is fighting its way into our woods and my compost pile. I am constantly hacking it back and adding it to the burn pile. Don't know if this is variegatum bboy mentioned above, but it has variegated foliage in silvery white and light green.