[photo by Gary]
Case in point: this potato plant, which sprouted in my garden from discarded compost (see front center, along the edge). A chunk of raw potato must have had an "eye" (that's the place where sprouts emerge from a potato after you've had it awhile) woke up, and started putting down roots.
When I noticed this plant I recognized it as a potato and left it grow in situ. When the above-ground foliage dies back, then it's time--as the locals say--to "raise" your potatoes. then I'll find out whether it's red or white, and of course the size of the individual potatoes attached thereunder.
I've been accused of being kinda with OCD or anal about keeping my garden spiffy. This more panoramic photo could be Exhibit A, but bear with me:
You can see the volunteer potato plant at the left-center front. But immediately behind it is a row of volunteer sunflower plants, which emerge every spring from last year's sunflowers. I transplant them into a row from their various sprouting locations throughout the garden. And the cool thing is that we never know what we'll get, since we plant several varieties of sunflowers from seed every year.
If I were truly afflicted with OCD, these volunteers would not stand a chance. Instead, I welcome them.