Before anyone can make sensible suggestions they'll need to know where you are situated geographically.

But to be frank those two little spots look a bit awkward and pointless to me. They're too small for anything other than annuals or one perennial and are likely to get walked over by anyone cutting the corner of your driveway or following the path of those white stepping stones. I'd be inclined to continue the stepping stones or fill the space with cobbles.

I'd consider two of the same small spreading trees or shrubs -- something that allows you to keep the trunk area quite narrow and let it spread above. One of the crepe myrtles might do it if they are suitable for your area.

PS Your garden so far is super pretty.

Anything tree size could obscure the road when pulling out of the drive. Anything low and spreading would overflow onto the lawn, killing the grass or onto the sidewalk, obstructing pedestrians. And although the two straight sides may be three feet this isn’t a 3 x 3 space. It’s much smaller. Not big enough for a shrub really.

some ideas:

Good ideas as usual, Dig Dougl

About a carefully selected and pruned (when young) tree obscuring traffic, I don't know so much. Thank how many residential areas in the world have street trees. I have a crepe myrtle just inside my gate at the end of the driveway, and a small maple (municipal) just outside it on the sidewalk. I have no trouble seeing traffic as I pull out.

I envisage this kind of thing:

That is completely out of scale for such a small area!! It would look ridiculous to have a tree of that size (or even smaller) shoehorned into that tiny area. Some low growing sun tolerant ground cover - perhaps sedums - would work best. Or just fill with river rock to accommodate drivers that may not make the turn into the driveway with complete accuracy :-) Or remove the edging and just let the lawn fill in.

Just because it may be a standard practice in your area does not make it good design.

Your grass looks great! So lush and green.

I’m not fond of mini-beds. They tend to make an area look spotty and cluttered. I’d do away with them.

Gardengal is on my wavelength regarding this space. I don’t get having a paved path almost to the sidewalk and then stopping at a curious little quadrant of garden., forcing the pedestrian to step sideways onto the drive. It’s a fussy little patch that will get walked or driven over.

Repeating the stepping stone pattern like at the house near the driveway corner would be a nice touch. A small tree would look good toward the other corner just not in the corner. The tree limbs would be a problem for people walking by and for your neighbor using their driveway. If they have to prune the tree to use their drive it could ruin the shape.

I'm sorry, but I think those little corners are just silly.

Still smiling at your indignation, gardengal. Sorree.

Ja, I do know the difference.

I'm in agreement with all who don't think the spaces don't work. Too small, fussy and close to drive, even for small tree. They need to be 6' x 6' for SMALLEST tree. Going to be obstructive with shrub or many perennials in that position. Going to be stomped if annuals or low perennial. Better as in Groveraxle's picture. Or, if the patio stones exist, add the corner ones.

On another point, when making quarter-circle beds, the edges should be quarters of real circles ... not fluctuating, curvy angles, which ends up looking very unprofessional.

I think the spaces might have to work because that looks like artificial lawn to me. My suggestion is a bed of mostly Echeveria with some tiny Sedum if you don't like any soil to show. The bluish color will look nice against the dark green lawn.

Curious how you get such a green lawn there? But you’re asking for drought tolerant plants? I’m in the NorthEast so we don’t have drought like you guys do; so I was just wondering.

If the OP wants something at the corners, why not....no different than columns at the entrance to a drive. The only limitation is install nothing that impedes vision or traffic patterns.

I agree that something along the lines of an exclamation point could work. But for the overall yard size, it can't be pole thickness plant. A 3' diameter "exclamation point" would work but would need to be set back from the drive and walk a bit, so the space, as is, is too small to work well.

I think we are debating the finer points of design & it simply comes down to aesthetic interpretation.