You mean back by the boulder? I'd put in ferns. The marginal Wood fern might be native to you, is reasonably deer and bunny resistant, puts up with dry shade (once established, water it well in the first year or two). You can sprinkle a few shade-loving plants among the ferns, if you like.

Love your property! (New England?) Stone adds so much character to a garden, and you have it in abundance. Are those old foundation walls? You have a wonderful opportunity for gradual development for years to come, to enhance the distinctive natural character that is already there and to plan interesting journeys from one great area to another one that offers a completely different feel. Done well, it will seem like it has been there for centuries.

I assume you have probed the soil and know that the ledge underlies the entire area between boulder and the building near it? A pond would be lovely, if possible, but as @Sigrid suggested, a fern grotto would be beautiful too. If this photo was taken in the afternoon, then that area faces south and probably gets quite a bit of sun, so you will have to choose sun-tolerant ferns.

Here's an edited photo with a few other ideas that seem appropriate to the property, planting "gateway" trees (sugar maples?) at the entrance to the firepit area and screening it off a bit so it feels more like a place apart. I haven't shown much green, given the season of the photo, but have left spaces for perennials among the dormant shrubs. (This also shows a small pond--wishful thinking!)

This suggestion is a variant on Sigrid's idea: