I started with a USPS small flat-rate box, and lined the inside with a gold H&M bag. I think some scrap fabric or scrapbook paper would also look swell. The box was then filled with homemade caramels, kraft paper confetti strips, a star sparkler, and a "happy birthday" garland printed on to kraft paper and strung on to baker's twine.
I also threw together a quick card to stick on top. Now that I think about it, a balloon would totally be a great addition, too. You can also add in whatever store-bought goodies you want to send along, and scale this up to humongous sizes, if you'd like. I'll probably be returning to this "birthday box" idea over and over again in the future for all my friends! You should try it out, too.