Being a n00b here, I'd say you'd probably have to give us a picture of the leaves to help us ID the plant. My guess from the crazy root system is that it's some type of grass. I'd wait for input from others though, heh.

Sorry about that! Hope this helps.

Not 100% sold on it looking exactly the same but maybe couch grass.

The roots or probably rhizomes look far too thick or fleshy for couch grass ( Elymus repens).

It is probably some native plant or weedy perennial, no grass.

Alstroemeria?

What grew there last season because certainly this plant was there at that time?

FataMorgana

there arent many things.. that gratuitously die.. because you pull the leaves off ... as compared to pulling up the crown or the whole plant ....

time to get out the spade.. and dig it up..

or let it releaf.. and spray it down .. if its everywhere..

ken

Yes Alstroemeria is better for the roots but foliage may not be quite right. Diligent picking off of the shoots will eventually wear it out, whatever it is. But you have to keep at it, the usual problem most people have with trying to starve a herbaceous plant out with top removal is they let it go too long between assaults and it manages to make and store a little food each time.

Certainly a closer look at the foliage would help an id.

Yep.