This appears to be a Black Walnut (Juglans nigra) nut, and it is common to find them shedding once the nut inside is mature and ready for dispersal by wildlife. Squirrels are a common consumer, though we have limited information on how many other wild animals can crack the hard husk and eat the seed. Lots of insects utilize the foliage as caterpillars or other larval stages, which in turn feed a range of resident and migrant songbirds. If you're curious and want to break open any husks to see the seed (nut) inside, use caution because the plant's juices stain skin, fabric, and concrete brown.

If the identification of walnut doesn't seem to match the tree's appearance, please share photos of the foliage and the overall tree and we'll try to ID it.

Miri