300 seeds. Alyssum saxatile. Perennial. 
 
Also known as Aurinia saxatilis. Hardy in zones 3-9.
 
Height 10 inches. Spacing 15 inches.
 
Sowing Alyssum Seeds
 
Sow seeds outdoors in late spring. Or start indoors 6 weeks before the last frost date. Barely cover the seeds with soil. Full sun.