Hi Kimberly,
May is just around the corner & I know you are super excited about your upcoming trip! Also love that you are planning ahead to save money & having water & snacks delivered to your room is a great idea. The people at gardengrocer.com have always done a great job for us.
You are more than welcome to bring bottled water, food & drinks inside the park - we do every trip. There are a couple of exceptions to this - no glass containers (except baby food jars) & no alcoholic beverages.
You are also welcome to bring a cooler for your food & drinks as long as it is not larger than 24" long x 15" wide x 18" high.
There is a link on the Disney website that lists items that may not be brought into the parks - click
here.
I always bring a couple of Ziploc baggies with me. They are great to have on hand in case you have some leftover carrots, grapes or other non-perishables from a meal that you can save to snack on later.
If you are visiting Disney's Animal Kingdom park, you will not be permitted to bring in balloons, straws or drink lids as they are a safety hazard to the animals.
You will have to open all of your bags (purses, diaper bags, coolers, camera bags, etc.) when you go through security at the theme parks. Be sure you go ahead and have everything unzipped, opened and ready for inspection. That will speed up the process and get you into the park faster.
Wishing you many magical memories :-) Allison