There are only a handful of ferns in New England that remain green throughout the white season (I've already introduced Marginal Wood Fern).
Evergreen Wood Fern (Dryopteris intermedia, also called Intermediate Fern) is one such fern and can be found in circular clumps year-round. This fern has medium-sized (1-2 ft) fronds, with brown scales found low on the stems. By inspecting the lower-most (basal) pinnae, one can tell this species apart from others in the Dryopteris genus.
The inner-most pinnules of the lowest basal pinnae are typically smaller than the second inner-most pinnules, or at least no larger. (Does anyone know a less wordy way to say this?) Checking more than one frond is a good practice, as the basal pinnae are not always in prime condition. Be aware that several hybrids of Dryopteris species exist, so identification may be inconclusive.