Hi Marenda,
Thank you so much for visiting the Disney Parks Moms Panel with your question. It sounds like you are well on your way to creating a really special day for your son's fourth birthday. With a character breakfast, the Pirates and Pals Fireworks Voyage, and a birthday button, he is sure to have a spectacular day!
If you would like to add a little more magic to his day, I suggest that you work with
Disney Floral and Gifts to create a unique gift for your son. We did this for a birthday for my daughter one year, and were able to have them put together a nice package for her with a Minnie Mouse plush and balloons. They have gifts for every age and with many different themes. Once you have perused their website, give them a call at 407-WDW-GIFT (407-939-4438) to speak directly with a Magic Maker who can help you to customize a gift for your son.
Disney Floral and Gifts has cake options as well to enhance your birthday celebration. If you are looking for other cake options at Walt Disney World, you can call the cake hotline at 407-827-2253. There is great information about cakes at Walt Disney World at the unofficial website disneyfoodblog.com. Once you are there, search for "cake" and you should be able to find the cake frequently asked questions page.
Another idea for making the day special for your son is to let him chose all of the attractions that you will take in on his birthday. If you are visiting a theme park, allowing him to lead all of the decisions about what to ride, see, and do, can be really special for a young child.
I hope that these thoughts are helpful for you, Marenda. Have a wonderful time planning your special Walt Disney World celebration, and please do not hesitate to ask if you have any further questions.