New to the forums...have searched and did find a some good posts on many of my issues. Now I need to tackle trying to somewhat level and get real grass growing. I guess I am at a loss as to where to start?

I am in SE South Dakota (zone 4) and have the most lumpy yard I have ever seen! It has, granted, been neglected horribly over the past 5 years or so but the lumps predate the neglect (my soon-to-be ex-husband really did nothing more than mow). The lumps and subsequent low patches have a 2 to 4 inch difference in height (perhaps more) and the high places are very pronounced. It isn't that there is a whole area that is high or low, the entire lawn is lumpy. I notice, unless mower as high as it goes, I shear off the tops of many lumps while mowing -- which I do frequently, taking off as little as possible, do have good sharp mulching blade on mower. Initially I did bag, just to get some of the weeds out an not just back into the lawn -- now am mulching as the weeds are more under control and not seeding out.

I spent the past couple of months trying to overcome a horrible weed problem (crab grass, thistles, clover, dandelions) -- took two raised garden beds down to soil intending to replant next spring. This has helped the weed issues as they are not seeding out in these beds and spreading. Do have foundation beds surrounding the house and also wrapping most of the fence line with some nice perennials, bushes, roses, etc. These I have been hand weeding with great success. Time in pulling out thistles/other weeds has gone from several days/week to one quick evening.

I would have loved to go organic, but the weeds in the lawn were beyond that. Have sprayed the weeds in the lawn about weekly and believe I have good handle on them. Using Ortho product for weeds and crabgrass. Will say, though, that even green mowed weeds look better than unmowed lawn or dead weeds :) I have noticed the grass coming slowly in where the weeds are going out.

Now, I know I have work ahead of me...but am at a loss as to where to go from here?? In the back yard especially, grass only grows on top of the lumps, then the valleys are nothing but soil. Do I try to roll them out? Do I water, top dress (with ???) and drag? Should I just try to overseed this fall and ignore the lumps?

Help??

Thanks for your time...am good with roses, but admitted novice with lawn care.