What feast does Piggy supply for Ralph and the fire builders?
Piggy provides a "feast" of fruit for the boys. This comes late in the novel, when many of the "bigguns" have already moved to Jack's camp, where they are presumably feasting on slaughtered pig. Due to their unusual circumstances, the boys in this group cannot hunt, but they have thought of building a fire right near their own shelters, & they feel the need to celebrate. Piggy and Samneric sneak away while Ralph drifts in his own thoughts, then return with a surprise:
He came to himself with a jolt. Piggy and the other two were by him. They were laden with fruit.
“I thought perhaps,” said Piggy, “we ought to have a feast, kind of.”
The three boys sat down. They had a great mass of the fruit with them and all of it properly ripe. They grinned at Ralph as he took some and began to eat.
“Thanks,” he said. Then with an accent of pleased surprise—“Thanks!”
Although it may seem like a poor feast in comparison to what the hunters are eating, it means the boys can celebrate their companionship, & their last few moments of peace before all hell breaks loose on the island.