Could this tree (or one nearby) be a Chesnut or Chinkapin/Chinquapin (both genus Castanea)? These look like chestnut seed pod husks, which are notoriously very bristly-spiny and fairly large for a tree seed pod. If the tree ID is unknown but it has not fruited in years past, perhaps it is only now old enough to start producing fruits (nuts in this case). It's not uncommon for nut-bearing trees to not reach reproductive age for a decade or two after planting or germination.

If not chestnut, there are many types of insect galls (odd tumor-like plant growths) that can occur on a variety of trees (often oak) that may look alarming but which cause no damage to the host plant and don't need treatment.

Miri