Hi Vanessa!
You are indeed one of the lucky ones to live about half way between Disneyland and Walt Disney World to choose your vacations from. Both are so unique in their own way and both should be destinations for all families if possible.
Guests are allowed to bring items into the parks with them. Many choose a sturdy backpack as their carrying device as it is easy to tote around. Glass containers are prohibited so be aware of that as they will confiscate those during security checks. Liquids in plastic containers are fine. You may also bring in snacks and there really isn't a strict rule on this. Please look through the
Park Rules and Regulations as that might answer many of your questions.
As a mother and grandmother my advice for snacks is to keep them simple and compact. Goldfish crackers, peanut butter crackers, and granola bars are perfect to hold you over until meals. Make sure whatever snacks you bring are non perishable as the sun's heat will bear down on you all day. If possible keep things with you that are not too salty as that will only lead to you needing more liquids to satisfy your thirst. There are some great snacks offered at various locations throughout the parks so don't try to bring in everything or you will be sorry for weighing yourself down.
Disneyland does offer several sizes of
Lockers for rental to their guests. This is often a great way to store your snacks and drinks you are not using at the moment so you are not having to carry things around the parks.
Enjoy your Disneyland day!