Devil's Hopyard is a small state park and the campground here provides open sites with a few large trees near a stream and across the street from a waterfall. There is a slight slope to some of the sides, Latrines are provided, but water is not; due to contamination, you'll need to bring your own. Picnic tables and fire rings provided. Sites 4 & 5 are next to the latrines. Sites 1-3 have a slight slope. Sites are large enough for an RV. Cell phone coverage poor.
Sites are inexpensive if you are a CT resident, only $14, but there's a $10 surcharge for out of state campers (2021). The season opens early, in April, and runs through early October. On a Wednesday afternoon in July there were still 5 site available for the upcoming weekend, so it may be a reasonable option for last-minute plans. And by mid July they are allowing campers without prior reservations, but no guests (again, 2021 COVID restrictions)
Available activities include hiking the trail network, fishing for brook trout, picnicking near the river, or mountain biking.