mac and cheese 1 pound pasta per 8, 1 quart sauce and 1/2 to 1 pound cheese per pound

green beans- 24 pounds ready to cook per 100

rolls-2 per, 2 pounds butter per 100

two watermelon fruit baskets- weigh your fruits, so you don't run out- see the fruit tray page

cake- a full sheet cake serves 50. To reduce the high cost of the wedding cake, consider having a smaller decorated cake and either/or a grooms cake (2 layer half sheet, chocolate is popular)) and a kitchen cake (same flavor as the wedding cake, but sheet cake).

bottled water-2 per person
tea- 8 gallons per 100, 1/3 unsweetened

Strongly suggest you add an appetizer table, and here is why:

Why You May Need an Appetizer Table
A self-catered buffet is a real challenge to the organizers, and things don't always come together as smoothly as hoped. By planning and setting up an appetizer area or "nibble table" which is ready when the guests begin to arrive, the cooks and servers have time to complete the arrangement of the dinner buffet. This is especially critical if there are children among the guests, or there is a wait before dinner, as at a wedding reception.

This does not have to be complicated. Three items, plus a punch, or two if one is alcoholic, are sufficient- 8 gallons per 100. Typically, include a fruit tray or possibly a relish or antipasto tray, a cheese tray and an attractive dip or spread; or you can go with a dinner theme such as TexMex with chips, salsas, Texas caviar and guacamole; Italian with bruschetta or antipasto; maybe shrimps or other cold seafood, if budget permits.

One appetizer service area is needed for each 100 guests.