the goldfish plant can be pinched back - you will get 2 branches from just below where you pinch, almost in a Y formation. I have pinched mine back several times, and it's a much fuller plant. It does look a little wild right now because of all the new growth, but I'm thinking of repotting it into a hanging basket this spring. I have found it to be a very fast-growing and fun plant - it's one of my favorites right now. Enjoy it!

I agree with floral_uk; it does look like loosestrife. here in Oregon is is a noxious weed that carries disease. Without being able to see it up close, it's tough to be sure. It is a possibility that it might be Epilobium (fire weed), but the shape of the inflorescence leads me to believe it's Lythrum salicaria.

wet leaves complicates it a bit ... but daisy comes to mind ... some of them can be prolific seeders ... do you have any around???? if we fail here.. try the botanists in the name that plant forum .. ken

Leucanthemum vulgaris, the meadow ox eye daisy type, would have a basal rosette, and they don't grow rhizomes (IME). Symphyotrichum (aka Asters), would be my bet too, I planted/ handled some several times, this foliage reminds me of S ageratoides, only problem there are several species, sub-species and cultivars, so really tricky to be sure which it is, plus I have no clue whether they could prosper without winter dormancy, good luck, Lin