We just had our farm field trip yesterday. We are blessed to have a historical farm, with animals right near us.
Doing my farm unit right now
For my PreK class I am also doing this, I got the idea from a "Mailbox" magazine:
on a brown bag glue a copied black line master of a simple barn. on the side of the barn I wrote a letter, either the first letter of the students first name or the first letter of their last name (I tried to get as many different letters as possible.) I send these home attached to an instructions sheet asking the child and parent to find things that start with that letter. (no food or breakables) when they come back we sing this for each child. "farmer Suzie had a barn, ee, ii, ee, ii, oo. and on this barn there was an 'S', etc, etc. then I have the child take out the things and name them , show them to the other students and repeat the name and it's starting sound.
All week we talk about how important farms are to us and I show pics of farms and discuss how we get our food from animals and plants on a farm. I have several humorous farm stories as well. I also include several different types of sequencing, dot to dot, and cut and paste worksheets with farm themes on them.
I know there is much more I can do, but I am only a morning preK and required to include a regular curriculum of academics as well.