Recently I saw a packet of flower seeds in a store. They were yellow alyssum. I did not know that alyssum had yellow flowers. http://www.pinterest.com/pin/56787645279898531
Alyssum Saxatile is a very common prrennial over here Petronius. Excellent ground cover plant with silvery leaves and flowers that come in all shades of yellow from a pale lemon right through to a deep golden yellow. The Alyssum you're thinking of ( white/pink etc ) isn't really called Alyssum ( that's just a common name ) it's proper name is Lobularia.
Petronius....you sound like me...we both need to stay out of the stores.....lol. Brought home more bulbs...they jumped in my cart and when i got home...there they were. Daggone Walmart
After researching Alyssum Saxatile, I was able to learn that it is ideal for a rock garden, for dry, sloping ground, or for edging garden beds.