A farm theme will provide children with bushels of fun. If you can, provide some bales of straw; little kids will love climbing and balancing on them. Suggest that everyone wear overalls.
For each guest, cut out a simple barn shape from red construction apper; cut a T-shaped slit for double doors. On a piece of white paper, draw the outline of the barn with the doors open. Write the party particulars inside the door outline and photocopy as necessary. Cut out the white barns and glue one behind each red barn.
Frost a square or rectangular cake with milk chocolate frosting. Divide the cake into penned areas, using fences from the craft store. Install a little garden of green gumdrops, into which you insert the birthday candles. Add crumbled wheat-biscuit cereal mixed with sugar for hay; brown sugar crystals for chicken feed, and green sprinkles for grass. Set small plastic farm animals around all but the crop areas.
Adapted from The Parents Party Book: Fun and Fabulous Theme Birthday Parties for Children 2 to 8 Years Old by the Editors of Parents Magazine. Golden Books, New York.