LOL! This is an interesting question! I did not know they were edible, first of all...second, I think they would do a number on your body. I found this information on Wikipedia...
Foam peanuts, also known as packing peanuts, are a common loose-fill packing material which is also used to prevent damage to fragile objects during shipping. They were introduced circa 1965. They are roughly the size and shape of a peanut (in its shell) and usually made of polystyrene. They are shaped to interlock when compressed and free flow when not compressed.
In the early-1990s, a more environmentally friendly starch-based alternative was developed. One of the first brands of biodegradable peanuts, Biofoam, is made from the grain sorghum; other brands are made from corn starch. Biodegradable foam peanuts have no electrostatic charge, another benefit over polystyrene. Being biodegradable and nontoxic, they are also edible. Two of their main drawbacks are a lesser resilience and higher weight relative to polystyrene.
Starch-based peanuts are soluble in water, and polystyrene peanuts are soluble in acetone, but not vice versa. Because polystyrene peanuts are non-soluble in water, they are also used as a light-weight aggregate in hydroponics.
And I have to say, I would only eat the bio ones if I had to eat any...LOL