Antennaria alpina is a small plant that forms tight mats of gray foliage with tiny, fuzzy whitish pussytoe flowers.  It grows to 6" high.    Grow in sun to part shade in well-drained, gritty soil.  Tolerates both dry and moist conditions, as long as excellent drainage is available.   

A variable species with a wide distribution in the Northern Hemisphere, this subarctic perennial extends as far south as Montana in the US. Works well in a small scale rock garden, trough or container.  It should be extremely cold hardy, given its native distribution, Zone 1 Asteraceae

Antennaria dioica is a drought tolerant groundcover that creates dense mats of white, spoon-shaped leaves with spikes of fuzzy, white to pink pussytoe flowers in late spring.  2-5” X 18”.   It does best in full sun in well-drained soil with low water.  It can be used in a sunny rock garden as small-scale groundcover or bulb cover.  Native to open areas in the Northern hemisphere.  Zones 5-9. Asteraceae

Low mats of silver-gray foliage and fuzzy whitish pussytoe flowers with noticably dark bracts.    Grow in sun to part shade in very well-drained, gritty soil.  Boulder Mountains, ID  Asteraceae