I am not sure what I found. After a recent rain, I found the wormlike creature on my sidewalk. It was very flexible and even tied itself into a knot and was able to untangle itself. My first thought was a centipede or millipede, but I could discern no feet or antennas on it. Nor did I see any segmentation. The diameter of it was so small, that I could not tell through my fingers what it felt like, although it seems to have a hard skin (exoskeleton). It wasn’t soft like a worm. In the picture, I believe the head is in the lower right corner, away from the penny. It wasn’t easy trying to get it in focus. I let the guy (gal?) go. Most likely I will never see another one again. (If it helps to identify it, I live in La Crescent, MN)
Your is one of two letters that arrived the same day with images of a Horsehair Worm or Gordian Worm. The other letter is from Nebraska. We found a great site with more information.