Sunrise at Stonehenge

My guess would be "No". I base that only on the fact that tickets are reserved for a specific time (you can walk up and buy a ticket for the soonest time of course) and the venue does not open until 9:30 AM.

It appears that the tour companies have a lock on both a tour that early, and access to the circle, which also is not allowed on a normal visit.

Yes! You will need to book your early entrance tickets ahead of time.
Here is the info I postedhere after I purchased our tickets. We purchased evening tickets but you can easily purchase morning sunrise tickets too.

Yes, go to Stonehengetours.com they do sunrise and sunset tours. Premium Tours also does sunrise tours, both companies cost £135.00.

Buy them on your own, we did sunrise a few years ago. Basically a security guard escorts you all out there and just hangs out while folks take pics etc. you can walk among them but just cannot touch.

You can do it on your own. Book "Stone Circle Access" through English Heritage; that is the only way to visit the henge outside of the general public opening hours, which are in the middle of the day. They have multiple time slots in early morning and in the evening. You will need to book far ahead (check how far ahead they are accepting bookings) and look up the time of sunrise on the date(s) you are going to be in the area.

A few caveats. Be aware that others, including the relatively high-priced tours, are trying to do the same thing (ditto for sunset) so it will be harder to align with sunrise/sunset than with other time slots in the "Stone Circle Access" schedule. There's no public transport that will get you to Stonehenge before sunrise, so unless you book a tour you'll need to rent a car, and that means finding your way there in the dark. If you're late, you lose your visit -- the shuttle bus won't wait for you. Be aware that it may be too cloudy for the sunrise (or sunset) to be visible on the day you go. As Mark Twain said, everybody talks about the weather but nobody does anything about it -- so you just have to take your chances.

Despite all those caveats, we did it and it was fabulous. We went during the general opening hours the preceding day, to enjoy the visitor centre and a walk around the henge outside the ropes using the audio guide -- and practice the route from our hotel. That was a great orientation & helped us to fully enjoy our early morning stone circle access the next day.