I can't tell if this is something I planted or a weed. Also, I have many sensitive ferns in this area. Are they a valuable specimen or should I remove them?
This looks like it could be New York fern because it appears that the frond tapers in width as it reaches the ground.
Sensitive fern can be a bit "aggressive" so whether you want it or not is just something you need to decide for yourself. I have brought some into my garden and so far it is ok, but I might think differently in 5-10 years, I don't know.
Thank you for the ID. I found this:
Threatened and Endangered Information:
Thelypteris noveboracensis (L.) Nieuwl.
This plant is listed by the U.S. federal government or a state. Common names are from state and federal lists. Click on a place name to get a complete protected plant list for that location.
New York fern Endangered
New York fern Exploitably Vulnerable
Can you explain what exploitably vulnerable means?
No, I have not heard that. I wonder if they meant the habitat is threatened?
Plenty of it down here! It's a fern that spreads around in favorable conditions.
Endangered: means that the overall population of the fern in the area of question is limited in distribution and is vulnerable to total loss. Generally this implies that there are relatively few populations even though each population may appear common locally such an occurrence is so limited as to infer that any loss of any existing population would emperil the species within the area of question: Illinois.
Exploitly vulnerable: means tht existing populations can be seriously decimated by commercial or individual collectors.