When I sent cookies I would wrap them in plastic wrap with wax paper between the cookies (so they don't stick together), then put them in a ziplock bag, seal all but the corner and use a straw to suck the air out, then zip quickly and put into a ziplock or glad ware plastic dish with a slice of bread. Brownies I just baked in gladware baking dishes that had lids, I can't find them anymore though.
You can make cakes in a jar (and I'm sure you can breads in a jar), you'll need wide mouth mason jars for this, plus really good bubble wrap (the best I found was the one with big bubbles). Wash your jars, grease them (do not use pam), mix up your batter, and fill jars about half way (you don't want them to bake up to the top of the jar), bake, put rings and tops in water to boil. When cakes are done (I think it only took like 30mins.) carefully take out of oven and put a top and a ring onto still hot jar, you'll hear a little pop as the jar cools, the jar is sealed! Do Not Frost cakes before sealing, the frosting will go bad, just send the frosting along with the cakes.
I never got any complaints of spoiled food. The cakes in a jar were a big hit.