Bringing a 2-year-old. Is proof of age needed?

Hi all. My husband and I are bringing our almost 2-year-old to Disneyland in two weeks. We already have tickets for ourselves, but I’m wondering what I need for my son. I know kids under 3 don’t need a ticket- but can we just walk right in with him? Does he need a wristband or something? I don’t want to get to the gate and then be turned away because I didn’t get something important he needed. Thanks for your help!

EDIT: Thanks all, very helpful advice. We will plan to stroll on in!