Gotta love the off-season… and some of the comments from previous finders helped too! I struggled to find all three sisters in the summer but now, in the fall, the finding was a snap! The oak for the second stamp has been cut and now has shoots growing out of the stump. In summer, "green, leafy plants" abound. But in the off-season, I found the perennial shrub easily. FWIW, I would describe it as a yucca-type plant.
These are great stamps. Glad they are all still active! This is such a neat spot!