Greetings, Mariana! How lovely that you are bringing your daughter to the Disneyland Resort! I have taken my daughter to the Disney Parks since she was just a toddler and she continues to love the parks more and more as she gets older.
You are correct, children under the age of 3 do not require a ticket at the Disneyland Resort. Also, you do not need to bring anything to validate her age.
You should also know that you can bring in your own stroller or
rent one. I always suggest having a stroller with little ones at the Disneyland Resort. It's not only an efficient way to get your child around the parks, but it serves as great storage! We keep an extra change of clothes, wipes, sunscreen, and lots of snacks in our stroller whenever we go. Additionally, there are many
attractions that do not have any height restrictions. This means your daughter can enjoy riding with you on Astro Orbitor, Alice in Wonderland, Buzz Lightyear Astro Blasters, The Little Mermaid ~ Ariel's Undersea Adventure, nearly all of the attractions in Mickey's Toontown and "a bug's land," and so much more.
I hope this information was helpful. Have a wonderful day!
-Linda M.