Hi Heather, welcome to planDisney!
Thank you for bringing your question to us, I'm happy to help! And a very HAPPY BIRTHDAY to your son!
When the
Disneyland Resort re-opened, a
theme park reservation system was implemented, requiring Guests to have both a theme park reservation and a valid
theme park ticket to enter the parks. While you can absolutely buy tickets at the gate, there is a chance that reservations for the day will be booked. I recommend taking a look at the
Theme Park Reservation Availability Calendar to see if there is availability on the day and park you would like to attend. There is different reservation availability for one-park per day tickets and park hopper tickets, so please do look at both options!
Unfortunately, per
Disney's Stroller Guidelines, wagons and stroller wagons are not permitted. BUT, the Disneyland Resort does have
strollers for rent, so hopefully, that can make your travel a bit easier. And since you have a little one, I also want to mention the amazing
Baby Care Centers at the parks! They offer a clean and comfortable facility with changing rooms, nursing rooms, a feeding area with high chairs, and more.
Finally, children under the age of three do not need a ticket to enter the parks. So, if you plan to attend the parks before your son turns three, he can enter free of charge! In the past, my wife and I visited the parks a few times when our daughter was under the age of three. We were never asked to provide proof of age for her. However, if you feel more comfortable, you are more than welcome to bring a copy of his birth certificate.
I truly hope you're able to get a reservation to visit and celebrate your son's birthday!
See ya real soon!
Jin