The Little-black Stoneflies and Little-brown Stoneflies have been hatching quite well. Look for the aggressive rises of trout along the margins of the stream as they chase the egg-laying females skittering on the surface to drop those eggs. So far, from all the reports I have heard, the fish aren't looking up and taking them, but you never know.
The early seaon Blue-winged Olives, Baetis tricaudatus, have also been hatching fairly well on some streams, and that can only get better as spring approaches.
Here's a Little-brown Stonefly catching some rays on a streamside stone.
Photo by John Collins
Get out and fish! And sharpen those hooks.