Go ahead and eat them!
They can regrow from their bulbs if they weren't harvested last year. This regrowth can be eaten, but you'll want to focus on the fresher, greener parts for the best taste and texture.
Here is what to consider before consuming:
Inspect the spring onions for signs of spoilage or disease. They should be firm and vibrant in color, without any mushy spots, mold, or unusual odor. If the onions have developed a slimy texture or an off smell, it's best to discard them.
The new 'fresh' growth that emerges in spring tends to be the most tender and flavorful. Older, more fibrous parts might not be as pleasant to eat (often bitter) but can still be used in cooking where they'll be softened, such as in soups or stews.
Clean the onions to remove soil and debris by rinsing them under running water. Peel away the outer layer if it looks damaged or dirty.
Safety: As a general rule, if the plant looks healthy and is growing vigorously, it's likely safe to eat. Just ensure you properly clean and inspect it before consumption.
Remember, the quality and taste might vary depending on how well the plant has overwintered and the conditions of the current growing season. Eating spring onions from your garden that have overwintered and sprouted anew can be a delightful way to enjoy early produce, but always err on the side of caution and discard any that don't seem right.