It is that time of year when the green liners show their ugly head! When new greens are constructed, contractors would put a plastic liner between the sand and the out lying native soil. Most people think this is to prevent grasses from creeping into the green. It is not. The purpose is to prevent the native soil from sucking the moisture from the sand, causing the edges of the green to dry out. Liners are rarely used anymore because recent research has shown it to trap gases under the green.
In our case, the freeze/thaw action over the winter pushes the liners out of the ground. Every spring we have to cut an inch or two off. Sometimes we even have to make a trip around in the summer. Hopefully this explains the appearance of the mysterious liners!