Not sure what they are but they are harmless. Only 3 in the US to worry about, Black Widow, Brown Recluse, both deadly, and Tarantula, no worse than a bee sting usually. Those are none of the dangerous ones. I don't have my book with me so I can't look them up but I do know they are not Black Widow, Brown Recluse or Tarantula.
Got a few the past couple of days using a Pentax 50mm f1.7 with 45mm of extension tubes. fun trying to get close enough and get good focus, but with flash it does a great job. These are no more than 1/4 inch long.
OK correction, this one is a little over 1/4 inch...but not much