Part of the difficulty you may be having in your search is a confusion of the terms. Horticulturally, a 'shade tree' is one that casts shade rather than one that prefers shade to grow. It's a common mistake :-) If you were to search under 'shade tolerant' or 'woodland trees', you would likely have better results.

Depending on how much shade exists (not altogether clear from photo), a few possibilities for you are Japanese and other Asian maples, kousa dogwoods, magnolias, stewartia, Styrax japonicus. All should suit your zone.

I do have one Dogwood Kousa in the far right corner, but it's not shown. My yard is much bigger than one is shown, but this is the area in question. Where two oaks are, is the North side of the yard. It gets some early morning sun for two or three hours. I actually had a company out for inspection in hopes of pruned the three oaks (one isn't shown). They didn't recommend it, saying the trees were extremely healthy. Part of the pruning that I wanted would have been taking just few lower limbs off.

Do these pics help? The first is to the left and other is just to the right of the 2nd oak.

It doesn't necessarily have to be maples, but if I had maples it would be well away from the house! I did do the shade tolerant search, but nothing really stands out as aesthetically pleasing to me. I'm trying to start from the back and work forward with 'layers' as I have read.

In addition to the smaller understory trees gardengal suggested, medium to large flowering shrubs can be part of the layering in a well designed garden. Shrubs to consider are viburnum, hydrangea, witch hazel, rhododendron, Fringe tree, even holly to name a few.

I've been looking at hollies. This year I bought several Viburnums and several hydrangeas. They are small now of course. I'm just really getting into shrubs and trees. I was stuck on annuals and perennials for far too long. I still love them, I just want more diversity!

I'm wondering if I wouldn't be better off choosing trees more in front of the oaks. Smaller trees of course. Redbuds, Japanese maples, Dogwoods. So many choices and not enough knowlege!

Some specimen small understory trees would make a fine layer in this setting. From there the next layer is shrubs.

The grass actually grows between the roots at the trunk. I didn't even think of this! Duh!

I've spend hours looking at trees until my head hurts. I usually do overthink things like this, because my sense of style is rather lacking, as is my experience with trees and shrubs.

I really do thank you both!