Rattlesnake Fern,  Botrychium virginianum
Ophioglossaceae or Adder's Tongue Fern Family

A medium-sized fern with a single, large leaf which is divided into leaflets that are divided into smaller leaflets, which are deeply lobed into still smaller leaflets.  The leaf branches from the stem about halfway up, the stem continuing up to form the fertile (spore-bearing) frond, which is branched and carries the spore-bearing structures.  The fertile frond is green, turning yellow in late summer.  Supposedly the fertile frond resembles a rattlesnake's rattle, hence the name.  The leaves are deciduous and die in the late summer.

A woodland native.  Occasional in the forests of Wildwood.

Cutleaf grapefern (B. dissectum) is similar but smaller and with a more widely branched fertile frond. The branch between the fertile and sterile leaves is very close to, or even under the ground, so it appears to be 2 plants.