(Editor's Note: this article was originally published on March 5, 2008.)
My gift plant turned out to be a Cheddar pink, Dianthus gratianopolitanus 'Bath's Pink', a short-lived perennial. Dianthus are called pinks because the flower edges look like they were cut with pinking shears. They grow wild in Cheddar Gorge in southwest England, giving the flower and the local cheese its name. Cheddar pinks (sometimes called just pinks) is the common name for Dianthus.
Dianthus are botanically related to baby's breath (Gypsophila) , thrift (Armeria), Maltese cross (Silene) and even amaranth.  The genus contains annual, biennial and hardy perennials like sweet Williams, carnations, clove pinks, gillyflowers and Cheddar pinks. More than 300 species exist, ranging from 2 inches tall to 3 feet tall. Most annual Dianthus sold by garden centers in spring are Dianthus chinesis. Pinks come in many colors besides pink: salmon, red, fuchsia, purple, white and bi-colored.
A mat-forming evergreen perennial, Cheddar pinks make a fragrant ground cover, border, and do exceptionally well planted in rock gardens and wall crevices. Cheddar pinks are subject to root rot if the soil is poorly drained. Do not heavily mulch (even in winter) except in high rainfall areas where pea gravel may be used to keep the foliage clean and dry. Cheddar pinks require good drainage, a sunny spot and neutral pH to bloom in mid-spring. They do best in zones 3 to 9.
Allan Armitage declares the species Cheddar pinks to be one of the best of the genus and says they are almost indestructible in his Georgia garden. Dianthus 'Firewitch' is on his recommended list.
Cheddar pinks are propagated by heel and tip cuttings or by dividing right after flowering. They spread quickly in good growing conditions, making divisions easy. Companion plants with similar dry growing conditions include Siberian iris, Coreopsis, Nepeta, Plumbago, garden sage and lamb’s ears. They also complement blue-foliaged ornamental grasses and perennials.
Some Cheddar pinks cultivars:
'Tiny Rubies', double dark pink flowers
'Baby Blanket', pink flowers
'Mountain Mist' has similar pink flowers but has bluer leaves
Dianthus Star Series 'Arctic Star'
'First Love' Dianthus
Dianthus arenarius 'Snow Flurry' (the Finnish sand pink)
'La Bourboule Alba' is 4 1/2 inches, with white flowers
‘Cranberry Ice' offers brilliantly fluorescent, single petals of red splashed with lavender-pink.
Two antique pinks are the 18th-century, 30-centimeters-tall ‘Inchmery’, rare but worth hunting for in specialty plant nurseries. It has double blooms of delicate blush pink and good tolerance for heat and humidity. The legendary Dianthus ‘Mrs. Sinkins’ (20 centimeters tall, hardy to zone 5), is a 19th century double white with an almost overpowering fragrance and petals so profuse the flowers resemble little cabbages. 
Many Cheddar pinks are hardy from zones 3 to 9 so there’s no excuse not to tuck these into your garden!
Thanks to Victorgardener, kropit and Equilibrium for use of their photos from PlantFiles.
North American Dianthus Society