It is called swag, which some people believe stands for "Stuff We All Get" (the more PG version of the two variations).
Another relevant expansion is "Souvenirs, Wearables and Gifts" (ref)
Wiktionary defines swag as
2.Handouts, freebies, or giveaways, such as those handed out at conventions.
It seems that in written English, swag is the way to go:
Perhaps the most definitive answer stems from an entry in Francis Grose's Classical Dictionary of the Vulgar Tongue(1823), with a couple definitions for "swag" including:
SWAG. A bundle, parcel, or package ; as a swag of snow, &c. The swag, is a term used in speaking of any booty you have lately obtained, be it of what kind it may, except money ; as where did you lumber the swag? that is, where did you deposit the stolen property? [...]