I have a raised bed out in my yard near the road (in front of my house) that I just finished seeding with some greens of various kinds (spinach, turnips, arugala, romaine & swiss chard) It's quite the eyesore, because it's just made from stacked white sandbags, and has nothing around it but a six-inch mulch strip and grass. I don't want to put border plants around it because I'll be tearing it down after this growing season, and I want to be able to mow easily around it on a riding mower: But I'd love to mix some flowers in with the veggies, to make it look more decorative. I've mixed bunches of marigolds in with things in summertime - but I hear they hate cold weather? (I don't really know a thing about flowers)

Whats a good flower choice that won't hurt the veggies and can tolerate the cooling weather?