Hey there, Tracy! Welcome to planDisney, we are so glad you stopped by! One of the greatest things about Disneyland Resort is how accommodating they are to all guests who visit. Cast Members take the time to ensure their guests feel welcome and are able to provide (in this case!) meals that everyone can eat. It is one of the many reasons why my family and I continue to visit Disney Parks as often as we can!
I went on the Disneyland website and found that you can make special dietary requests to Disneyland within 
14 days of your arrival. Email Special.Diets@disneyland.com, with gluten-free requests if you are planning on eating at table service, and some quick-service restaurants during your visit. I researched some restaurants online and found that you can purchase a gluten-free Incredicookie over at 
Jack Jack Cookie Num Nums at Disney's California Adventure Park, and at Clarabelle's Handscooped Ice Cream, several flavors are gluten-free, you just have to ask. Over Disneyland Park, you can check out the gluten-free desserts at 
Jolly Holiday Bakery & Cafe, as well as DOLE Whips at 
The Tropical Hideaway and at 
Tiki Juice Bar. 
Have the most magical visit to Disneyland, Tracy!
Frances