It Started With Small Melilot
My own difficulty in identifying specific Melilotus species was greatly assisted by csledge, an iNaturalist I have never met. She identified an observation I had posted, including an exhaustive botanical reference list that is amazingly handy!
Here's her ist of online resources as a starting place for identifying MN and N. American species: https://www.inaturalist.org/journal/csledge/55746-a-list-of-online-resources
Many thanks csledge!