I just stopped back to have a look at the plants again. I did take a couple of quick phogtos but was going to say that the plant itself looked like tall blades of grass. So Yellow Star Grass may be a good id.

Thanks, Remy, that is correct. The plant is next to an oxalis. The leaves are long and oblong opposite each other on the stem with blunt ends. I think Carol23 is correct, the plant being Valeriana ozarkana, especially since I live in the SW Missouri part of the Ozark Mountains. Thanks Carol! Jill

Cynara cardunculus, Cardoon?

Looks like Persicaria pensylvanica. The name you were probably thinking of is lady's thumb, which is Persicaria vulgaris. It's possible it is that species but that usually has chevrons on the leaves.