Niagara Trials Riders (NTR) Club website has changed over to the TeamUp calendars. There are five trials clubs in NY and they essentially keep the master calendar for the state.
The combined NY State trials calendar also has a link to the D6 (PA) Teamup calendar. Lots of trials riding opportunities in that area - almost every weekend from May through October! See the combined calendar here.
MATT (Mid-America Trials Team, MO) has their local club schedule and Central Regional Trials Calendar embedded on their web page. If you are in and around the Kansas City area they can fix you up. They even have a 2-day vintage event going on in May.
The club has previous experience with the TeamUp calendars using them back in 2017. Check out their implementation here.