I was on a walk

When it comes to wooded areas, they are generally worked in by other magickal practioners. The place you found may be a site for a coven. If you feel the trees crossing over is where a portal lies, its best to walk around it, not through it. You won't enter into any place because portals are spiritual, but walking through such energy can leave you feeling odd, sick, or just plainly strange because your energy mixes with it.

If you feel welcome in the area, then it may be a great place for a ritual or spell, but if you do not feel welcome, then it's best to keep walking and leave it be. You don't want to mess with such things when you don't know the nature of them.

I've seen many such places. In the woods where I used to live near, by the Desplains River, there were many. One in particular that I will never forget was a circle about 10-15 yards wide created by dead trees. In the center the ground was burnt (a bond fire I assume). Many times these aren't natural creations and were specifically positioned for ritual work.