Throughout the Seder, there are a number of food items which remain on the table, some of which are consumed during the service. Thses are the food items on the Seder plate, the matzah and the wine.
The Seder plate has on it Karpas (greens), salt water (to symbolise the Israelites tears), Charoset (to symbolise the mortar of the buildings), the Pesach, or shank bone (to remind us of the Pashcal lamb sacrifice), the Maror (bitter herbs) and burnt egg (the egg symbolising the Spring festival nature of Pesach).
There are three pieces of matzah on the table used ritually, although there are normally many more pieces to be placed in chicken soup or salt water soup (traditional starters for dinner). The three pieces are placed in a matzah cloth, and are revealed and consumed at certain stages throughout the evening. After the meal, the leader of the seder has normally hidden the middle piece of matzah somewhere in the room for the children aorund teh table to hunt for it. They then ransom it back, and this piece, called the Afikoman, is then shared out for everyone to eat.
We take a drink of wine at four different points during the service, although this is not all it is used for. When we count out the Ten Plagues, we dip our finger in the wine and place a drop on our saucers, one for each plague. Elijah's cup is usually placed in the middle of the table.