Can you help me identify this weed? It's infesting our lawn and garden in...
Your description sounds like nightshade, however we cannot see any flowers in focus and can't say for sure which nightshade it is. Possibly Eastern or Southern Black nightshade. Try Google Images of the weed and flower to see if that is what it is. These are annual plants and must come back from see each year, so DO NOT ALLOW ANY SEEDS to form and fall on the soil or else you'll continue to have the same problem.
I googled Nightshade; that's not what this weed is.
The flower of this weed is under 1/2 inch across and has small, lavender, daisy-like petals. I'm sending 2 more photos of the flowers, one including a trowel with a 5" ruler for scale. The online photos of nightshade show small flowers with a yellow center and 5 white petals tapering to points.
This weed is a perennial, not an annual: individual plants come back each year, larger each time. They have a substantial root system, including a central taproot typically 8" long or longer.
The veins on the undersides of the leaves are green, not red.
Your plant is Elephantopus spp. , commonly called 'Elephant's foot'.
Yes, that looks right. Thanks!