Quite possibly Onoclea sensibilis - Sensitive fern.

This is one of the Grape Ferns, maybe Sceptridium/Botrychium dissectum or similar

Of the botrychiums, what about rattlesnake fern since mine is deciduous?

The leaves are wrong for Rattlesnake Fern, which has leaves that are much more dissected. B. dissectum's sterile leaf turns dark bronze in winter, and is replaced the following summer. I can't find any other deciduous grape ferns to match this plant. Perhaps the dark colored, winter leaf makes it appear deciduous.