It's a fireweed relative, fringed willowherb. Epilobium ciliatum (fringed willow-herb): Go Botany Despite being a problem in contains particularly, it is actually a native plant.
Hey, @Bryan_, thanks for posting that. I pulled one out of my container of strawberries last week. I was thinking of asking the ID, but decided I wanted to give the berries a better chance after pulling out another plant that was taking over (and adding some new soil), so I opted to just do it in.