Solved Knot like roots surfacing in lawn

I moved into my home a little over a year ago and shortly afterwards noticed some roots exposed in the lawn. I didn't think anything of it and just dug them up and filled in the holes. Unfortunately the problem has got progressively worse ever since. I am finding more and more knot like roots in my lawn and it's killing off the lawn. The knots are about the size of a squash ball. I had some concerns that it may be Japanese knot weed so I left everything to grow for a few weeks to see what appeared. A number of plants appeared in the area where these roots are appearing with green leaves with red edges. These plants appear to be coming out of the roots, however, I've been unable to pull one up that is connected to the knotted roots because the knotted roots near them broke up when I dug these plants up. This means I can't be 100% certain these plants were actually growing out of the same roots but it would seem very coincidental if they were not. I'm a complete novice when it comes to gardening but to my eye these look nothing like Japanese knot weed. I've attached some recent photos. Can anyone tell me what these plants are and how I can control them? Are the roots likely to be from these plants?

 

Welcome to Gardeners Corner digby280. I can't identify the plant but I suggest that these are suckers growing from the roots of an established tree or shrub, either in your garden or a neighbours that have spread beneath the lawn. Have a look around and see if you can spot the parent plant.

 

A nearby Plum tree would be a prime suspect, although a parent plant might appear different to the suckers if it's a grafted tree and the suckers are coming from a rootstock, such as plum, which was used for grafting a non-plum tree.

 

Thank you Sheal and Scrungee. It seems pretty clear now these are suckers coming from the tree below. Are these lumpy knot-like features on the roots normal?

 

The lumpy knots are quite normal, often a result of continual cutting of the suckers by the mower. They can also develop canker. All you can do really is try and remove the roots which are causing a problem, it wont harm the tree.

 

It looks like a young Copper Beech to me but I'm sure Silver Surfer will correct me if I'm wrong.

 

Very similar to the suckers that arise from my peach tree.