Red Berry????????????????what is it
Those red berries are the poisonous fruits of an aggressive arum commonly referred to as Lords and Ladies, Arum italicum. Discard the seed stems in the trash, NOT the yard debris bin.
It's an herbaceous perennial (dies down for the winter) and is a difficult plant to eradicate. You may be able to dig it out, but be certain to get rid of all root fragments. Discard in the trash.
Here's an information page about this arum - https://weedwise.conservationdistrict.org/arit-2.
And this is a report describing successful treatment with 2% glyphosate (Roundup) - https://depts.washington.edu/hortlib/student_research/2016/zmallon_poster2016.pdf.