Candytuft is native to the Mediterranean region and is related to cabbage, broccoli, etc in the Brassica family of plants.
For Wikipedia info about this interesting plant, check the bottom of this post.
Here is some with a Nasturtium, also grown from seed.
(BELOW) Also establishing in the same garden bed is a young Golden Privet. It's planted with some Helianthemum which bears dark orange flowers and gray foliage
Also naturalizing nearby is some tough-as-nails Yellow Loostrife AKA Circle Flower. The blooms last a long time and it's very undemanding.
Perennial candytuft (Iberis sempervirens)
Iberis is a genus of flowering plant belonging to the family Brassicaceae. It comprises herbs and subshrubs of the Old World.
These species are commonly known as candytufts. The name "candytuft" is not related to candy, but derives from Candia, the former name of Iraklion on the island of Crete.
These plants provide nourrishment for a number of insect species of which the rare Euchloe tagis butterfly is the most striking example as it is monophagous on species in this genus.
The Portuguese Dappled White (Euchloe tagis) is in the Pieridae family of butterflies.
It ranges through Southern Europe where it is found from Portugal to Northwestern Italy and Northern Africa (local populations in Morocco and Algeria).
This species is found in local, discrete populations limited to fairly small areas of suitable habitat which is invariably made of calcareous outcrops with Mediterranean scrubland where the foodplants, crucifers of the genus Iberis are to be found.