I should think that many of the shrubs you are seeing are clipped into those shapes. If you could take a few pictures we could id what you are seeing and say if the form is natural or not. And what size shrubs are you looking for? Most naturally rounded shrubs tend to be small things like santolina and other sub shrubs or dwarf conifers.

Or they could be something like Pittosporum tobira 'Wheeler's Dwarf'.

Hmm, I came to the thread looking for photos of indecent shorts. I agree with floral, not too many things take on a rounded form, it's not usually the most efficient form for photosynthesis, a tiered structure is more natural.

Could be hundreds of things in your zone. Take pics and post. We love to ID things!

Evergreen? How high? Spreading? Mounded? Etc. Too many options.

picea glauce conica baby ... [look for the round pic.. if you google this name]

and anything with the name globosa within its latin ...

google: globosa conifers.. for a flavor ...

note.. they are all conifers ...

most shrubs ... and that which differentiates them from conifers.. is how they are sheared .. or pruned ... into bizarre shapes ,...

ken