Dandelions were brought to North America as a food crop. We can eat every part of the plant. They're an invasive species, but not what I would consider a weed.

Theres only one plant in my yard i consider a “weed”. It grows almost like a carrot or a parsnip. But it grows a long thick root straight down and has a small leafy part on top. And when you pluck them out it leaves a cone shaped hole. No clue what it is but ive been calling it a tuber lol

Lol, you don't put Roundup on your lawn unless you don't want a lawn anymore.

2,4D is the stuff that kills "weeds" but not grass.