Turning your yard or living room into a barnyard isn't as daunting as it sounds. To greet your guests, make a banner that says "Welcome to the (your last name) farm". Have some farm animals roaming in your front yard. To make them, cut out the shapes of cows, horses and sheet from sturdy poster board, decorate them to make them look like the farm animal in question. Glue wooden sticks to the back, and stick them in the ground around the walkway or driveway.
Make a pig pen full of pigs using a playpen or pack 'n play, and pink balloons. Draw pig faces on the balloons, and use pink curling ribbon to make tails. Put them all in the playpen or pack 'n play. You can use brown construction paper to look like mud, if you'd like. Let the guest play with your pigs during the party.
If your child owns a barn toy, use it as a centerpiece on the food table, and cover the table with a red and white checked tablecloth. Put cutlery in a terra cot flower pot, and use red bandannas as napkins.
If it's available, and you don't mind the mess, scatter a few bales of hay around the room or yard. If your party is outside, the bales can be used as seating for younger guests. Corn stalks add a nice touch also.
Make a scarecrow using an old pair of jeans and a flannel shirt. Stuff the clothes with newspaper, and put a straw hat on top. You can make him stand up in your yard by threading a shove through the pants and shirt, and then sticking it into the ground.
If your party is going to be outside, fill a small wading pool with water and lots of rubber ducks, to make a pond. Be sure the pool is always supervised, for safety's sake.
Make a barn with a large cardboard box, appliance sized would be ideal, painted red. Fill it with your child's stuffed animals and some hay, if you have any. Place rocking horses and stick ponies outside the barn. Let your guests play with all the animals during the party.
Farm food is good food! You can do a BBQ, with hot dogs, chicken, and burgers, or go with a picnic lunch that includes sandwiches, potato salad, chips and watermelon. Use tin pie plates or clean metal buckets to serve the food.
For snacking, make a bucket of "chicken feed."Combine snack mix with candy corn, and serve it in a large, clean metal bucket. You can provide miniature metal buckets for the guests to eat it out of, if desired.
Make a lollipop flower garden. Cut flower shapes out of different colored craft foam, and slide the lollipop sticks into the foam to make a flower. Attach a leaf to the stick if you would like to. Stick all the lollipops into a large piece of craft foam. Let your guests pick and eat the flowers.
There are lots of options for the cake. You could serve cupcakes with toy animals on top, or you could make a traditional cake with a farm theme. Some suggestions:
Bake or purchase a 9x13 inch cake and a loaf shaped cake, in any flavor. Cut the 9x13 inch cake into a barn shape. Use the loaf cake as a silo. Trim the top into a curved shape. Frost both cakes red, and use white trim on the barn and silo. Use rectangle crackers for the barn doors, yellow tinted coconut for hay, and a wheat cracker for the door in the hayloft. Crispy rice cereal squares can be used as hay bales. Add some plastic farm animals, and you're done!
Another choice is to use a 9x13 inch cake to make just the barnyard, and put a toy barn right behind the cake. Frost the cake green. Use squished graham crackers on one section as a corral. Small pretzel twists pushed into the icing make a great fence around the corral. Put some plastic farm animals inside. To make a pig sty, squish up some chocolate wafer cookies, and make a pile of the crumbs in one corner of the cake. Put a plastic pig in the middle of the pile to complete the look.