My ammonite collection is growing. All collected from the same site in central Montana. I don't know if all are the same type or not. I have found some huge ammonite pieces but not a whole one yet. I'll keep trying. Went up to Deadman's Reservoir yesterday and the water level is way down and lots of small bacolite pieces and other stuff around for the picking. Good luck!
That is a very nice assemblage! I heard that there are some fossils to be found north of Lavina. Also if you go just south of Lavina, cross the Musselshell and take the first left (east) and go about 100-200 yards and to the right at the crest off the road you can oyster shell fossils.