For my daughters first birthday I wanted to have a theme, mostly because our friends have kids that were 2-3 at the time, so I wanted it to be fun for them too. We did a little barnyard theme from 1stwishes.com. I loved the little banner they had we had it say "Giddy Up and Have Some Fun, Madelyn is Turning 1" Then we took pictures with her in overalls and pigtails, next to my cowboy boots and her little barn toy for the invitations. It was adorable. Our plan was also to have it at a park so we had the playground for kids to play at, then at the end of the summer before I had bought a blow up pool for like a dollar and at christmas I bought bags of those colored balls and we made a ball pit "Pig Pen" I also threw a few pig stuffed animals from the dollar store in there for the kids to play with. My sister made an amazing cake, it was shaped like a barn and she also made cow and pig cupcakes. They were awesome!
It was cute, fun, and easy, and all the kids (mostly my daughter) had a great time.