Sinkhole?

Not sure what we have in our front yard on the grass and on the edge of the sidewalk but it is a growing hole. Called Town Engineering and they indicated it was not their responsibility though they may send someone out to check. Any recommendations of who I might call to look into this? Thanks in advance. 

Picture?

I can send a picture later today - probably about the size of the circumference of a standard outside trash can - and about 1 ft. - 2 ft. deep. Neighbors have mentioned that there may have been a tree planted at this spot but later removed - unsure as don't know what to look for if this was the case. Any advice/recommendations? 

we had on like like about a year or so ago-discovered by our landscapers.  for sure from a previous tree location.  it was filled in with gravel & bricks and dirt.  it was a good 5 feet deep and 2 feet or so wide.

oots

You may want to place a visual warning , such as taping off the area to alert passers-by.  It does sound as if a tree was once there and this is the depression due to ground shifting. 

Yes - we already have two fluorescent orange cones surrounding the hole. Any suggestions of who to contact to assess the situation? 

If it seems likely that it was a tree, then probably a landscaper.  We've had a couple of tree depressions as old roots decayed.

Is it near your water line?  Most likely it is a tree, as everyone has said, but there is a slight possibility that a water leak has undermined the area.  Very slight, though.  I'd just fill it with dirt and see if it comes back

If solid on your property then I go with the Tree first.

Next I consider;

Oil tank that rotted out

Old Dry well that caved in.  I had on in Maplewood

Underground pipe leak like sewer

Thanks for all the comments. The hole is on the property right on the edge of where the driveway and sidewalk are located but on the grass. This area of our property is sloped down. Ultimately my concern is to rule out everything and anything other than the tree scenario as looks like the other considerations could be a lot more worrisome, unsafe, costly and intrusive. Looks like I might try contacting a landscape company and go from there. . . .