In the fall, we direct-seed and seed-start ten or so varieties of annual flowers that grow over the winter. The Bachelor's Buttons pictured above are a favorite because they require nearly zero effort between direct-seeding them in late September and harvest in early May.
There are weeds, bugs, freezes, diseases, and all manner of woodland creatures who could theoretically take out these hardy flowers, but none of them do, and every year we have a banner crop of bachelor's buttons.
Chamomile are probably the next-easiest after Bachelor's Buttons. We start them indoors, and plant them out around the same time as the BBs go in, and then we don't do much until harvest. By "don't do much" I mean, don't weed, don't cover, don't fertilize, don't tend, don't protect, but do often gaze adoringly at how well they're doing.
And in a close third behind the Bachelor's Buttons and Chamomile are these Dianthus that look a little worse for the wear right now, but they've gotten the same treatment as the Chamomile, and I'll be darned if we don't get five stems a plant from them: