Daisies have been used medicinally since the ancient Assyrians, who used it to combat eye problems. It's most common use, in ointment form, has probably been to treat wounds and bruises - hence its common name Bruisewort. Other uses over the ages have included to cure ulcers, arthritis, rheumatism and liver complaints.
The calendar suggests using it for coughs, dry skin and eczema. For coughs make a tea by adding 250ml hot water one to two teaspoonfuls of leaves and flowers, leave it to stand for 10 minutes and then strain. You should drink it three times a day. For dry skin or eczema you can add it to your bath water. Mix up equal quantities of dried pansies (flowers and leaves, daisies (flowers and leaves) and calendula flowers. Steep 30 grams of the mixture in two litres of boiling water for 20 minutes. You then drain it and add the liquid to your bathwater.
There's a lot on the web about daisies - growing them, their medicinal uses throughout history, legends and sayings. They come up a lot in literature too. So here's my "daisy chain" of links....
Four sites discussing the cultivation of daisies; medicinal and other uses throughout history; sayings, legends and symbolism regarding daisies :
Plants for a future
Flower and Garden Tips
Daisies in literature
Chaucer on daisies (scroll down)
Shakespeare on daisies
Wordsworth on daisies
Tennyson on daisies