Jenny Grumbles asked friends and neighbors for their leftover cereal boxes. Once she had enough, she created her first piece.

Companies make packaged food without synthetic dyes in other countries. But despite pressure from Robert F. Kennedy Jr., the change isn’t likely to happen quickly in the United States.

If I want a certain color with cereal, I have to be like, okay, let's go find that exact shade of pink. Okay, let's go through my pink box. Oh, look, there's not one in there. Let's go through all ...