Need a photo

Two shrubs looks unbalanced. You could remove one or add one. Personally, I'd add one and underplant with small spring bulbs to flower with, or shortly after, the dogwoods. Followed by some sort of spreading perennial plants like hostas or bleeding hearts which would lead out after the bulbs and cope with the shade of the Cornus. Hardy Cyclamen for late summer. Keep it simple. Btw giving your location would help people make practicable suggestions.

I'm not familiar with the tree (I'm in S Africa) but have looked on line, and I think they are planted far too close together to thrive. So I'd say centre one tree in that spot, and plant the other one on the opposite side of the lawn, at a diagonal if possible. There is something very lovely about having more than one of the same kind of tree in a garden. While they are small, I'd plant shallow-rooted annuals and spring bulbs around them (mulch in winter perhaps). As they grow you can decide if you want more permanent plantings and what they should be. Ah, but it is such a pretty tree, isn't it?

Having the box and pole just outside the bed makes it look off to me. I would want a more flowing contour to the bed, not a rigid circle.

Ideas using 3 trees/shrubs: