Disclaimer: I am not a dietician, but am just suggesting things based on my experience going gluten,dairy,soy and egg free. Please don't take my word for it, but feel free to check out for yourself if these items are free of allergens.
Below is a sample menu plan for the little picky eater. Click on the colored words for links to recipes.
Muffins and smoothies
Cereal (GF) (I'd suggest rice chex, Erewhon rice crispies, or Nature's path's GF cereal)
Breakfast cookies here or here
Granola and raisins
Hot dogs (Oscar Meyer all beef classic, or Applegate Farms)
Mac and cheese: Amy's Kitchen Ready Made or Cheese Sauce on Brown Rice Pasta
Chicken nuggets (Applegate Farms or Ians), and sweet potato fries (Alexia) or make your own by putting Gluten Free flour patted on Chicken pieces with salt and pepper and saute in olive oil
Veggies and hummus w/
Baked potato, Stagg's classic chili and bacon (I use farmland brand)
Hamburgers w/ lettuce or gluten free bread for a bun
Fish sticks and oven fries
Pb and Js on English muffins or Sunbutter!
Amy's dairy free burritos, or Food for Life tortillas with refried beans, and Pace Picante Sauce
To these meals can be added grilled broccoli or cauliflower (I put either in the oven at 400F for 15-10 min, rolled in extra virgin olive oil and salt. Delish!), fruit, veggies and cheese sauce, veggies and Heinz ketchup, veggies and hummus to round it out. Or a smoothie with some spinach or kale snuck in :0)
Veggies and dip (Kraft Italian or Annie's Roasted Red Pepper)
Fritos and fruit
GF pretzels and raisins
Ruffles with Ridges and hummus
Enjoy Life granola bars
Chips (Que Pasa or Tostitos restaurant style natural yellow corn) and salsa (like Pace Picante or a fresh Pico de gallo)