Are you thinking about having a 'Farmyard' party theme?
There are so many great ideas that can be used and you can do as little, or as much, as your time... budget... motivation and creativity allows.
From the invites to the food table, this is a theme that is so easy to pull-off and it's perfect for young children.
Here's a BLAST from the past:
When we had our son's first birthday (he's now almost 6!) we decorated our back deck with hay bales, brought in some chickens and dressed up in our cowboy hats and flannelette checkered shirts.
Check out a few other ideas here: