I would probably steer clear of the popcorn, as the corn itself is high in food chemicals.

My GF has followed this at times and is the queen of "white food" parties LOL. She does things like plain vanilla cupcakes with white icing (or pale pink using natural food colouring only), and white only marshmallows, pikelets with golden syrup, soft mild cheese & rice crackers, she also changes recipes with chocolate in to white chocolate, this doesn't set the kids off as much. She gives her kids the schweppes lemonade only, no other brands or flavours, unless you wanted to make up like a punch using pear juice & soda water etc.