Hey Howdy Hey, Lauren!
You've Got a Friend in Me here at the Disney Parks Moms Panel, and thanks for your question. You are so fortunate to receive the gift of a Disneyland Resort visit!
I'm delighted to tell you that you will not need to
purchase a ticket for your two-year-old son! Children under three years old are complimentary Guests of the theme parks. You will not need to bring any proof of birth date either. Keep in mind that you will need to include your son in the count when making
dining reservations, though, even if he will not be eating off the menu. This is to make sure there is a spot for him at the table.
Since you have a toddler, you will definitely want to make use of the
Baby Care Centers located in each park. These offer semi-private spaces to feed and change babies and toddlers as well as tiny toilets for potty-training tots. You can also purchase diapering and feeding essentials here if you forget anything.
I hope this helps, and please return if you have any other questions. See ya real soon!
-Jennifer