There were several of this kind in the nursery. Just leafing out, some buds already forming. A bird donation, or something worthwhile?

I'm just guessing at this point, Rob, but it may be a bird cherry or something along those lines? My bird cherry is budding now, and the leaves and bark of your plant look similar. Bud formation is different perhaps, but it's an avenue to explore.

Thanks Chelle - I'll look in that direction as the shrubs develop some more growth in the next week or two.

Small white flowers (some species are fragrant, too) might be another clue. Mine is a sterile cultivar, but I've heard that some of the others are distributed by birds.

Bird cherry as in Prunus species?

Prunus has alternate leaves.
The mystery plant is opposite leaved.