Chives are a great source of autumn nectar for bees and butterflies. Cut them back after they flower in the spring and they will flower again in August/September. They look great in a flower bed with other globular flowered plants of about the same hight. I like to mix them with globe flowers.
You can buy chives cheaply as potted herbs in most supermarkets and split the clump to make 3-4 plants. As an added bonus they are great cooking herb and are very hardy and easy to grow.