They are plants you don't grow for their looks, but for their smell. My garden has a surprising number of them. The basic herbs, of course, but then some you rarely find cultivated.
It took a while to find this:
It's the californian native Baccharis pilularis or Coyote Bush. Very common in the wild here, but few people ever buy it for their yard. For me, its scent instantly conjures being out in fresh air somewhere beautiful on the coast.
And then there's:
The Cleveland sage or Salvia clevelandii, a native of Southern California, which is extraordinarily pungent. I can just brush against it while pruning and have the scent on my clothes all day. It's delightful after rain.