Since there's nothing else nearby against the wall, I could see a little tree (made of a large shrub ... but not too large.) For example, a tree form deciduous azalea.

Thanks for the response. Sounds interesting - I will check into tree form azaleas. I don’t think I have ever seen one.

The wall doesn't look solid enough to me to retain a bed for either a tree or shrub. Also the soil is mounded up in away that is likely to wash out in future. Are you intending to improve the structure before planting? If not I think you'll be fighting a collapsing bed in due course.

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Bed was resized on the left when french doors were installed. The rest of structure has been in place for a long time. It is stable, but may be challenged by a tree. The mound you see is mulch that was pulled back to amend the soil. If not a tree, what would you suggest?

I think a tulip magnolia would be pretty there. What did you do?