Siberian Bugloss (Brunnera macrophylla)
This plant is not recorded as growing wild in the Pittsburgh area; but here it is, naturalized in Bird Park, Mount Lebanon, and blooming at the end of April in a corner of the woods where it was almost certainly not planted. Probably some seeds washed down into the park from the suburban yards on the hill above.
Siberian Bugloss looks very much like a species of Forget-Me-Not (Myosotis spp.), but is easily distinguished by its large heart-shaped leaves (thus the specific name macrophylla, which means “large-leaved”). Gray does not describe this species, but this quick description should make identification straightforward.