My daughter's 3rd birthday was in February and she wanted a Peter Rabbit Party. We couldn't find any Peter Rabbit invitations, so we copied an image from a book and made our own.  Since the kids were very small, we kept the activities quite simple.  As kids arrived, they went to our breakfast room, where they decorated their rabbit ears with veggie stickers, silk flowers, and spongey butterflies and dragonflies. I had plenty of stuff out with glue sticks. (I made the ear bases out of white poster board, and cut two tall ears, and a wide strip for each one.  Then I used double-stickey tape to put the ears about halfway down in the middle of the strip, and folded the bottom half of the strip over to make a strong base.) After they were decorated, we put them on to measure, then took them off and stapled them. (Be sure to write their names on the inside)  Next we all sat down and I read the Tale of Peter Rabbit to them. (Get a big version from the library.) Once they knew the story, we played Peter Rabbit Hide and Seek.  I bought an inexpensive straw hat from a craft shop, and the Seeker wore it and was Mr. McGregor. All the Hiders were Peter Rabbit, and everyone had a turn being Mr. McGregor. By then we were ready for cake. My daughter wanted cupcakes, and ice cream, so we tinted some frosting green, and luckily Easter merchandise was in, so I bought some inexpensive little wooden Bunny Easter Tree decorations and put one on each cupcake. (Be careful that the kids don't eat them!) We also served berries, and offered Chamomile tea, or juice.  We decorated our table with a bunny in a child's watering can, and had piles of baby carrots, brussel sprouts, parsley and tiny tomatoes in tiny baskets around them. I also made a little sign that said "Mr. McGregor's Garden"  After cake, they opened presents and just played. For take home treats, we included snack size bags of baby carrots, a small box raisins, and a little bunny along with their hats. It was really a fun party to do, not terribly expensive and just right for 3 year olds.