Hello,

I believe the plant is the start of a white mulberry tree, or Morus alba.  It is a weedy plant that tends to reseed in random locations. The leaves have varied irregular shapes. The white mulberry is considered invasive but its berries are attractive to wildlife and can be eaten by humans. While the berries are edible, the rest of the plant is poisonous. The milky white sap can also be a skin irritant and should be handled carefully if you should decide to remove it.
I have listed two links below with articles about the white mulberry tree.
Please read the articles and write back if you should have more questions. 

Thanks for asking Ask Extension.

Betsy B. - MGV

https://weedguide.cfaes.osu.edu/singlerecord.asp?id=77

https://plants.ces.ncsu.edu/plants/morus-alba/