What little concrete detail there is in the book:
The ground before the mouth of the horn splits in two and a round table with a snowy white cloth rises into the arena. On the table sit four backpacks, two large black ones with the numbers 2 and 11, a medium-size green one with a number 5, and a tiny orange one — really I could carry it around my wrist — that must be marked with a 12.
- Thresh - Since the District 2 backpack almost certainly contained Cato's armor, it seems likely that Thresh's pack included the same, or possibly a weapon. Given that he used a rock during the feast as a weapon (per the book), it seems like he lacked a proper weapon.
- Foxface - Given that she died later from eating poisonous berries, it's likely that her pack included food. Her scavenging indicated that she wasn't particularly self-sufficient in the arena, depending on grabbing what she could easily get from other, more successful tributes. Since she was back to stealing a few days after the feast, it seems likely the pack contained some food, which she finished consuming after those few days.
Unfortunately, the books are from Katniss' perspective, so they don't provide much additional information. The films show us many events that we don't see in the books simply because Katniss wasn't present to witness it.