Remember the four leaf clover you looked for as a child. Well they are edible. They are a member of the pea family.
While clover is largely considered as either a wild plant messing up your nice lawn, or animal food, it is a good food for humans. Clover is high in protein, vitamins and minerals. It contains beta-carotene, vitamin C, most of the B vitamins, biotin, choline, inositol, and bioflavonoids.
Clover blossoms and leafs can be eaten in several ways. Either fresh flowers or dried flowers can be steeped into tea. One of the easiest ways is to pick the young leaves and add them to salads. You can also prepare clover as a cooked green. Clover can be dried for later use.
Red clover also contains the blood-thinning substance coumarin. Coumarin is not unique to red clover; it is found in many other plants, including common grass. In fact, the pleasant sweet smell of freshly cut grass is due to the coumarin compounds. People on anticoagulant drugs such as Coumadin should be cautious of using red clover, as the blood may become too thin.
The University of Maryland Medical Center http://umm.edu/search-results?q=clover lists the following side effects
No serious side effects have been reported in people taking red clover for up to one year. General side effects may include headache, nausea, and rash. However, animals that graze on large amounts of red clover have become infertile. People who have been diagnosed with breast cancer should not use red clover without discussing it with their physician. Red clover may increase the risk of bleeding, particularly in those people who are taking blood-thinning medications.
As with any wild plant be sure of the identity of the plant before ingesting them, some wild plants can be poisonous. If you intent to use clover as a medicinal herb, I strongly recommend you do further research.