Palm Sunday: 

This is the day that Jesus rode into Jerusalem on a young donkey
colt. The people lined the way, waving palm branches and crying, Hosanna! Blessed is He who comes in the name of the LORD! 

Waving palm branches was a Roman custom that was used to welcome a ruler or king. The significance of the Palm branch lies in the fact that the people were welcoming Jesus as they would a new political leader. Jesus' message to them was symbolized in the animal that he rode. A ruler would have been riding on a horse. Jesus chose to come in a humble way. His attitude is summed up in Philippians 2: 5-8 (NIV): 

Your attitude should be the same as that of Christ Jesus: Who being in the very nature God, did not consider equality with God something to be grasped, but made himself nothing, taking the very nature of a servant, being made in human likeness. And being found in the appearance as a man, he humbled himself and became obedient to death--even death on a cross."

Decorate the table for lunch or dinner using real or artificial palm branches. Children might enjoy making the palm branches out of green construction paper.
Instead of placing the food on the table, leave it in the kitchen. After prayer, take turns serving each other the food. Even small children enjoy having mom or dad help them serve another member of the family. Talk about what it means to serve others. When we do we are serving Jesus. After dinner you might talk more about a servants role and how humbling it was to have the job of washing the people's feet. Take turns washing each other's feet. (Mom be prepared, this could get a little messy! Have lots of towels ready!)