Yes, they are edible.

 

Clover (Trifolium spp)

• above-ground parts can be eaten raw.
• best when cooked or dipped in saltwater to counteract bloating.
• flowerheads can be eaten raw, dried or cooked.
• flowerheads and seedheads can be ground into flour.
• sprouts have the best taste.
• creeping stems and roots can be cooked.

http://www.northernbushcraft.com/plants/clover/notes.htm