Sweet Alyssum; aka,
Sweet Alice, or
Seaside Lobularia
This tiny three or four inch tall honey-scented annual erupted in disturbed soil on the roadside, from a packet of wildflower seeds broadcast early in spring. Alyssum maritime or Sweet Alice is a most pleasant visitor that blooms at least from May to first frost, & here on Puget Sound it has a major winter rebloom.
Further south where they experience no frost, it is a tender perennial blooming year-round. But in temperate zones it does not easily survive the winter & is grown as a defacto annual, though a few seeds do seem always to bring a bit of Sweet Alice back in spring.
It does just fine in sunny neglected areas. It does fine without any watering early in the year when there is occasional rainfall, but if it is to keep blooming through summer the area would have to get a little watering now & then.
Cultivated varieties are larger & more densely flowering & come in different colors. The wild or semi-wild ones are tiny & white. They are not aggressive & vanish where larger weeds or flowers are competing for light & space. It can be used as a fill-in plant for front borders because it grows rapidly from seed, can be started just by sprinkling the seeds where little white flowers are wanted (with perhaps an eighth of an inch of soil over them), yet they will not demand space in the long run & as more significant perennials mature & spread, the alyssum can be allowed to fade away.
Originally native of southern Europe, but has naturalized in many places around the world.