Rhubarb flowers in bloom, seeds not quite formed yet.
Send to me be a Rhubarbcompendium reader, with permission to use (somewhere I have an email stating that).
Burdock is not rhubarb. Probably Arctium lappa or Arctium minus. The leaves, stalks, stems and roots of this plant are edible. For recipes see "Edible Wild Plants Of Pennsylvania And Neighbooring States".
Aphids under a rhubarb leaf.