Old Metal Church Bells

Today, I was at school in our school grounds area with my classmates doing a service project to pick up any trash or objects that didn't belong. I was in a wooded area and saw greenish object sticking out of the ground. I then began to dig around the object and couldn't believe what I was uncovering. It had some dirt on it and I brought it to a teacher that was supervising us and we couldn't believe what we saw. I attend a catholic school and so this was on property that is part of our church and school grounds. The bells are very heavy metal and has a green patina on it. The metal may be copper or brass? The large center bell has 1811 as you can see in the closeup photo of the center bell. The bells are very ornate and wondering if the 1811 could date back to the year 1811. Also, could they be original church bells from the early 1800's?