Food shelves and most of the organizations that share your stuff with folks in need must have something to send donations home in. Their preferred containers are paper bags. The sturdy ones with handles are the best. If you drop your stuff off in paper bags they can be re-used for clients to carry stuff home in.
Even better you can donate your stash of extra paper bags the next time you're in the neighborhood. As Summer rolls on many food shelves are able to send along home-grown produce to hungry families. Your bags will really come in handy then.
Make your bags a little more fun-ask your kids or grandkids to decorate them with their original artwork.