To stop erosion, I need a fast growing ground cover for several football size areas. The more invasive, the better - we are surrounded by a wooded area, so that would not be a problem. We have about 2 - 3 acres of land on a slight slope between the back of our house and a large pond with woods on both sides - this is in full sun. we also have another acre beside our house between our house and the barn that is mostly shade. We need something that once growing, we can just leave it alone and not mess with it. We have spent well over $2,000.00 trying to find something that will take over and spread and stop the erosion - but so far have wasted our time and money. I have thought about mint and thyme, but also would like to keep cost down with seeds - just don't know what plants or herbs will take off with seeds. Any suggestions would be greatly appreciated. Thanks!