goody bag

Short definition from Wiktionary

Noun

1. 1
   A bag containing candy, small toys and other goodies handed out as a thank you gift to guests at a children's party.
2. 2
   A bag (or just a napkin) containing leftovers (like cake or crackers) from a children's party.
3. 3
   A bag containing gifts and promotional material handed out at a conference, exhibition or similar event.