If the culms are smooth it's not Aureocaulis, as all forms of this have a rough,sandpapery surface. Allgold dose have green stripes but there usually very narrow and very sparse, I've never seen one with that ammount of striping. I'd have a go on Vivax, seems to fit you're description and photo quite well.

LOL, mxyplux, I was thinking it would be banana/date bread with peanut butter. Yeah....I was wrong. I'd still eat that, though, if I could skip the banana.... Annie

The raised planter is not big/deep enough to grow anything but green onions. Maybe getting rid of it and planting directly in the ground would be better. The space is so small it would be hard to get a lawn mower in there. I imagine grass would be a pain to maintain there. If you could use paving, consider discarded carpeting turned upside down, cut to fit, as temporary paving.

Options include: another deciduous tree that's already 5+ feet tall. conifers: Green Giant (widely available/affordable), Cryptomeria, Junipers. fast growing broadleaf evergreen: privet (ligustrum), American Holly (lots of choices) . A mixture is ideal, based on space, soil, sun. Enjoy!