Sometimes known as the seaside daisy (ht 40cm) this is a Mexican and Central American plant with a delightful haze of tiny pink and white blooms in late winter and early spring, though it usually seems to have some flowers almost all year round. It can provide a wide groundcover in areas where literally nothing else will grow. It likes sun and a well-drained position.
Once regarded as a weed, it has become more accepted in recent years as a drought-tolerant plant which is easy to grow! It does most definitely self-seed and has a habit of lodging itself in all sorts of nooks and crannies in the garden, between steps and in brick or stone walls. The effect is charming for those who don't mind a slightly wild look in their garden: those who prefer to keep the upper hand should probably avoid this daisy like the plague.
It should be cut back very hard in autumn to keep it compact; be assured that nothing will kill it, not even the most severe whipper-snippering by husbands who hate 'things hanging over edges'. It will regrow quickly to give lush foliage during winter. It can be cut back again in mid-summer if it becomes lanky; it will come back well in a few weeks. Note that - in my garden, at least - snails seem to like to hide beneath the curtains of foliage of this plant so that is a good place to look if you are doing a snail hunt!
A cultivar known as 'LA Pink' has larger, mauve-pink flowers (illustrated above) and is said not to self-seed like the original species. It can also be cut back a few times a year like the species to rejuvenate it.