Can you define "small" ? In tree terms that means very different things to different people so a maximum height and spread would be helpful in narrowing things down. And what are your soil conditions like - drainage, pH, availability of water, etc.

What part of USDA 9 geographically?

I live in Elk Grove, Ca.

I created a "no dig" garden area using layers of alfalfa hay, straw, manure and compost. I opted for this because of the hard clay soil we have so I put those layers on top of the clay. How do I determine the ph? It's in close proximity to the hose so I can water as needed. Drainage is good I guess as I don't see any standing water.

Trees 15 feet and under but more important is a smaller width as it will be close to the wall which is a little less than 6 feet high. I hope there are some trees that fit the criteria. I wouldn't mind pruning if needed to maintain size. I've seen a lot of nice images which are inspriring.

I did have some alphonse karr bamboo there but I spaced them too far apart and dug them out and put them in pots. I think i'd like more of the tree look. Maybe some heat-tolerant, narrow Japanese maple? I'm just afraid that they would burn up there.

Try investigating these small narrow trees for climate adaptability : Acer palmatum Tsukasa and or Azara microphylla varigata (pictured). Perhaps even an Cedrus atlantica pendula

Thanks for the suggestions. I will check those out. That tsusaka silhouette would be perfect but the local nurseries i went to didn't have any. They do have the weeping blue atlas though.

I'm also looking into the waxleaf privet but I read the blooms emit an unpleasant smell?

What about semi-dwarf fruiting plum trees, or pomegranates?

Adam you beat me to it. Why not consider a kumquat or blood orange.

Thanks, guys! I'll look into those.