Do you have a season in mind or will it be up all the time? This is exciting for you and a great compliment. The library is a good place to start. Childrens coloring books, expecially the ones from Christian bookstores should have some good pictures and/or ideas.
We were lucky when we did our church quilt. We had an architecht's sketch for the church and found lots of the other things for the surrounding blocks on the internet. ie St Claire, ST FRancis to name a few.
Good luck and be sure to post pictures.