Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
A few of these nymphs turned up in my kick net sample, with this being the only one fully mature and ready to emerge. It keys pretty straightforwardly to Ameletus suffusus, particularly because of the triangular dark patch on the labrum. The abdominal markings are close but don't quite match other drawings, likely just individual variation.
This mayfly was collected from the Cedar River in Washington on July 2nd, 2021 and added to Troutnut.com by Troutnut on July 4th, 2021.