Remind us again where you live? So you are interested in shrub layer ideas? Some evergreen and some deciduous? Do you have some favorite shrubs already?

Oops. Always forget that.

I live in Western Massachusetts not to far from Connecticut. And for shrub ideas I wanted something with yearly interest. I have heard about spicebush it I am interested but its hard to come by. And Pawpaws sucker a bit much for the available room.

And for evergreens. I wasn't thinking about them. I have small spruces and Firs in their already growing. Naturally there. Left them alone and they are doing fine.

Spicebush is great, but it is dioecious so you'll need a male and a female (unless you think there are others in the properties around you).

Other good shrubs:

Vaccinium angustifolium (low-bush blueberry), Vaccinium corymbosum (highbush blueberry)- both of which have great fall color.

Viburnum acerifolium (maple leaf viburnum), Viburnum nudum var. cassinoides (wild raisin) - again, both have good color.

Amelanchier arborea (downy serviceberry, shadbush, Juneberry), Aronia melanocarpa (black chokeberry) - these can be a bit bigger at maturity, so use as small trees. Great fall color as well.

By the way, good sources of affordable plants (they are smaller) are various state nurseries. I got 10 wild raisins from the New Hampshire nursery and they have done well.

Here is a link that might be useful: Good list here

I like those options. Easier to come by than pawpaws and spicebushes. But the Juneberry and black chokeberry are a bit big for the available space.

And what about creating some sort of vernal pool? Not a big one of course. Something small for the newly coming little guys. Anyone have an idea for that?

You might also consider adding Hydrangea arborescens 'Annabelle', blooms in shade and on new growth, so winter dieback shouldn't be a factor.
A vernal pool is a great idea! Great habitat for frogs, salamanders, etc., where they can survive without becoming food for fish. Birds and mammals also appreciate it for source of water and prey. Mosquitoes can be problematic, though, unless it remains dry throughout the summer.
I used a plastic liner, about 2½' deep.(They are available in various sizes from home improvement stores). Since it has no drainage, some water usually remains in it throughout the year. Taking advantage of that, I planted water/bog plants there. Iris, Arrowhead (Peltandra), Golden Club(Orontium). My resident bullfrogs also like the idea!

I put in in a Corylus avellana "contorta" (Harry Lauders Walking Stick) for winter interest. It tolerates shade well and is one of the few non-native plants that I intentionally added to my yard.

I also have a Hamamelis virginiana (common witch hazel), its a great shade loving shrub that blooms in winter.

I do have Hydrangea arborescens, as georgia rose mentioned. But I mow it off in the fall. Its a lovely shrub, great for the native shade garden. But I've found it needs more watering than care to deal with... however this year, that hasn't been an issue.

I also have hydrangea quercifolia. Mine is only on its second growing season, so I am not getting much from it now, but I am looking forward to it maturing and adding great fall color to my yard.

I like the idea of a pool too. That is my next project...

Maybe a clethra alnifolia. Maybe a native ninebark.

Here is a link that might be useful: clethra alnfolia

Mountain Laurel, Mountain andromeda, Leucothea are all evergreen shrubs. The andromeda flowers in late winter. Ferns, ferns, ferns will add interest. What I have done is use taller growing plants like Blue Cohosh the Baneberries and Snakeroot.