Daisies are herbaceous flowering plants that belong to the family Asteraceae which also has sunflowers, lettuce, and chrysanthemums. There are various types include the English, Shasta, Gerbera, painted, purple, blue-eyed, Oxeye, among many others.
This perennial flowering plant has various uses including some varieties that have edible leaves and flowers and medicinal properties (slows bleeding, reduces coughs and relieves indigestion). Also, they are popular ornamental or landscape flowers and for making daisy chains for children.
Do rabbits eat daisies?
Yes, rabbits can eat daisies including the Gerber, Marguerite, Michaelmas daisies among other varieties. They are safe and will not harm this pet in any way.
However, nutritionally, they may not present a lot of benefits. There are many other leafy greens you could opt for instead of these flowering plants. Go for asparagus, basil, Bok Choy, cilantro, dandelion greens, mint, watercress, wheatgrass, radish tops, turnip greens, kales, borage leaves, dill leaves, pumpkin leaves, among others.
If you plant them in your garden, it is normal for your bunnies to nibble them, if they can to access them since they are some of the annuals that these pets eat. 
Since bunnies are among the animals that eat daisies, if you do not want them to do so, some of the approaches you can use include a fence with a 1-inch or less chicken wire about 3 feet high, ensuring you bury it into the soil for at least 6 inches since rabbits do dig.
Also, you can try safe repellents including hot pepper, powdered fox urine, planting repellent plants, the use of cayenne pepper sprays, or restricting your bunny movement.
The question as to whether bunnies can nibble these flowering plants or not is yes they can. However, since they may not offer many nutritional benefits, it is not a good idea to pick them for your rabbits.
Ensure your bunny's diet has unlimited hay like timothy and clean freshwater as well as some fresh foods (10-15%). Let leafy greens make the larger part of your fresh foods with fruits and non-leafy veggies only being given as treats.