When making scramble eggs for a large group of people, once eggs are scrambled, add a tablespoon of sour cream and stir the eggs to coat. It will keep the eggs from turning green in the bowl. As far as the taste goes you can't even taste the sour cream. I did this for a large family brunch and it worked well.
I'm curious what caused your eggs to turn green in the bowl? I've never heard of that happening, but if so, I think it would be a safe bet to determine what caused that in the first place, before trying different additives, tasty though they might be.
Doing a search on green scrambled eggs gives the scientific reason eggs sometimes turn shades of green or gray after cooking and holding for a period of time...this is one I looked up myself since I"ve had it happen several times when cooking for a breakfast buffet and trying to keep scr. eggs warm. I've also read lemon juice or vinegar will also retard the process of the hydrogen sulfide in the egg white with the iron in the yolk to form iron sulfide. The sour cream is something I would try also. thank you