Ask Mr. Smarty Plants

From your description I am guessing that the fruit is from the tree Cornus kousa (Kousa dogwood), an introduced tree from Asia.  I'm not sure what the fruit looks like in the winter since I've never seen the tree in person; however, one of the photos on the webpage above has a very dark fruit that appears to be older so perhaps the fruits do remain on the tree in winter and are spiky and brown.  Here are photos of the fruits and leaves and a close-up of the fruits.  The fruit doesn't appear to be poisonous since I could not find it listed on any of the toxic plant databases I searched.  As for its edibility, some say "yes, but tasteless", others say "delicious."  You can read comments on the University of British Columbia Botanical Garden Forums.

Another introduced possibility is a tree from the Mediterranean region, western Europe and Ireland, Arbutus unedo (strawberry tree).  The USDA Plants Database doesn't show a distribution map for this tree but it might be able to survive in Connecticut if it grows in Ireland.  The inside of the fruit is yellow and it is edible and reportedly sweet and delicious.  Here are more photos and information.  Again, I don't know what the fruits look like in the winter.

There is a native shrub that occurs in Connecticut with a fruit that looks a bit like the one you describe.  It is Euonymus atropurpureus (Burningbush) and here are more photos.  Another native with a similar spiky red fruit, Euonymus americanus (American strawberry-bush), occurs in states adjacent to Connecticut.  All parts, including the fruits, of Euonymous spp. are considered poisonous if eaten in large quantities.

Now, for trees with brown spiky fruit in the winter, Liquidambar styraciflua (Sweetgum), is noted for its very spiky fruits.  They start out green, however, then turn brown with no, or very little, red in between.

If none of these is the plant with the fruit you saw, please visit our Plant Identification page where you will find links to several plant identification forums that will accept photos for identification.