Nice, thick, juicy Johnson grass tubers.
Johnson grass was apparently first BROUGHT to the US as a forage crop and I have to admit that the stems sure look juicy and the tuberous roots look good enough to eat fresh from the ground
BUT there are two dark sides to the plant. The first is that after it has been stressed by drought or frost/freeze, even walking on, it can produce a poisonous acid that can sicken or kill foraging animals like goats, cows or horses.
The second is the nightmare of many a gardener. It is VERY invasive and tough to kill organically without patience. If you are not concerned about the dark side of herbicides, then some of the popular glyphosate products will do the trick after several applications. I say several applications because it often does not reach the tuberous roots and it re-sprouts.
This is the same attribute that makes tilling and hand pulling challenging as well. Tilling just chops the roots to start MANY more plants and hand pulling usually leaves root pieces as well, just not in as many pieces.
The results of ignoring it are even worse as you can see from one of my garden beds left to "rest" over the past two seasons.
My choice is to hand pull until the energy reserves are depleted. The second round I may weed-eat at ground level like overgrazing would do and it continues to accomplish the same thing, starves the plant to death, but if I decide to plant something, then I will have to go back to pulling or possibly using a flame weeder. I originally liked that idea until I calculated how much propane that might take.