A box for Nan and Pop

Red Squirrel Phonics is a new series of decodable readers from Raintree, packed with real stories using words that children can read. The programme teaches children phonics skills in a sequential and systematic way so that they can learn the sounds (phonemes) and the letters that represent them (graphemes) and then practise and apply this knowledge through reading appealing, decodable texts that make sense. This ensures that every beginner reader will experience success in their reading from their very first book!

In this Level 3 book the family take a box of socks and jam to Nan and Pop. It seems to be rather heavy though. What else could be inside?