We're lucky around here. We've got both wild garlic and wild onion. But, we're jealous of yours. Outside of our garden beds, all we have is "good old Georgia red clay. Lots of stuff grows in it, but its as hard bricks, so everything has a hard time growing to its full potential. Ours never grow nearly as tall as those in your photos and the bulbs are much smaller.
RE: Finding edible treasures at the creek!