http://www.etsy.com/listing/122948848/superhero-birthday-backdropstars-and?ref=shop_home_activeI, personally, like this background the best. Without reading what the others have said, make sure it's a tad brighter. You don't want it to be in the direct sun, that creates too much shadowing. I would put all your items on this background too. Some of them would look nice if you hung a string across, then used a clothespin to hold the item on the string.
Taking pictures of banners can be difficult, I know for experience. Most of mine are 5 feet long and it's hard to get the entire banner in the photo without looking small and without shadows. Normally, the shadow castes is from me trying to get close for the picture. It takes time.
Practice with different things. You'll eventually find what you like.
Have fun!