Mystery Plant

Does anyone know what this plant is?

I planted what I thought was "Sweet Basil" in this pallet garden and when these odd plants came up I thought they were weeds. They sort of look like lilies. It's NOT basil. Initially I wondered if the soil packages I filled the pallet garden with had some rogue seeds mixed in, but the plants are coming up in pretty little rows! Then I thought it was a variation of basil as sometimes the Thai Basil has pointy leaves, but the leaves don't smell. After much deliberation I decided to eat a leaf. I know that's a little dangerous, but I didn't swallow, only chewed. It's definitely not basil, but it started to burn. So I'm at a loss, but I stopped weeding them out because I'm curious.

They were planted around May and they are only three inches tall so slow growing. This makes me think they are perennials of some kind.

Most of the plants have two stems. The plant below is mixed in with my prize lettuce. When the basil didn't come up I planted lettuce in it's place. This plant is a little larger than the others with three stems. I'm guessing it likes shade? Hmmm...

I love a good mystery. Gardening is always so rewarding.

Any ideas?