Gee, OP, I bet you never thought you'd be raked over the coals for having the gall to use the word "free" in your post...
Over the years we've received a number of small items sent to our homes: prints, postcards, magnets, pins, bumper stickers, etc. And an exclusive member magazine is sent quarterly.
More substantial items are often distributed at member events or meetings at the Disney resorts or
DCL, things like baseball caps, window clings, luggage tags, passport holders, beach towels, Christmas tree ornaments, etc.
Some of the items are funded by member dues. Some are funded by Disney as a sales and marketing expense. Nobody truly knows how the accounting works from item-to-item and event-to-event. It's well within Disney's rights to spend dues money on promotional parties and giveaways if they wish.
DisneyStore.com has a selection of DVC items available for purchase, and similar merch is stocked in most of the resort gift shops.