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.
This is a tricky one to ID. The forewings seem to be on the low end of the "crossvein count" key characteristic. There are paired marginal intercalaries in the middle area of the fore wing (kind of visible in photos, verified 100 % under microscope), and the wing and its veins are pale. Keys would seem to point to Callibaetis pictus in this case, but several other characteristics including size don't fit (pictus is smaller), and this is a bit out of its range.
This mayfly was collected from the Teal River in Wisconsin on June 10th, 2021 and added to Troutnut.com by Troutnut on June 11th, 2021.