Our weather has very likely already messed up any plans for getting those early plants in and seeds sown. No one has a clear crystal ball right for when consistent spring weather will happen. If you have sown seeds for later planting as transplants, keep them from getting any taller until they can go outside. Give them strong light and cooler nighttime temperatures than they have had, to keep them from stretching more.
Should we be worrying about any plants that are already up? Right now, it is mainly the spring bulbs and those bulbs are "smart" when it comes to how far the come up out of the ground. While some of the foliage could get damaged, the flower bud and stem remain below ground. Those bulbs in protected areas are always going to be ahead of bulbs in more exposed settings. It is common to see our very early woodland bulbs covered in snow and they handle that easily without any damage.
One fruit tree of concern, if you are lucky enough to have one, is peach. They do have a tendency to flower just as we are having that late frost or freeze. We can do something to delay flowering. If you go out now (although it is better done very late fall or early winter when the ground is already cold) and heavily mulch the ground around the peach, you will be keeping the tree from budding for a few days and hopefully miss that late frost. Straw has been the mulch of choice, as it is available now and easily removed. Use it later as mulch in between the rows in the vegetable garden.
The lawn remains dormant, except for those protected locations, just like the bulbs and our early perennials. If you have caught "spring fever," you can go out and hand rake the lawn until you are too cold and cannot hold on to the rake anymore.
Our ornamental flowering trees and shrubs have seen this weather before and are holding off on their spring bloom show until the weather improves. This does not mean you have to wait; you can have spring indoors. Go out and clip some branches from where they will not be missed later, and bring them inside to force flowers. A good tip is to wrap the branches in moist fabric, like an older bath towel, to soften the tight bud scales for 2 to 3 days. The warm home will trigger the flower buds to expand and open shortly after for your enjoyment. This does not have to be a one-time event either. You can repeat this until those plants begin to flower outside in real spring-like weather… whenever that will be.