It looks like Oenothera. You could start with O. biennis and O. cambrica as a try.

I have this plant to and no idea what it is.Mine grows 6ft tall or so and around 2/12 to 3ft wide and is covered with yellow flowers.Perennial here,doesn't reseed that I've seen and no idea where it came from.I've had mine for about 6 years.Bothers me to not know what it is.

This looks a lot like a plant called seedbox, Ludwigia spp. I think it is in the primrose family.
hortster

Here is a link that might be useful: {{gwi:304310}}

Have thick stands of it, really love

Could be Mullein..

https://www.bbg.org/news/weed_of_the_month_mullein

It is definitely not Mullein. Either Oenothera or Ludwigia, (as suggested 11 years ago!)

Hello. The plant in the picture is a common evening primrose. It's is not mullein, I grow mullein and am a certified herbalist. The leaves are not fuzzy and not big enough. This for sure is a

Jealous Gypsy Homestead & Forge This thread is from 12 years ago, but I agree with it is an evening primrose.