Americans for Justice in Palestine Action, or AJP Action, organizes Palestine Advocacy Days at least once a year, and this year they are again virtual, Sept.19-23.
Details: https://ajpaction.org/

AJP Action (an offshoot of American Muslims for Palestine) engages in lobbying and related activities as a 501(c)4 organization. See https://ajpaction.org/

Comment from Mehrene Larudee: The events have usually been well organized and provided good training about best practices in lobbying. It's not an all-day or all-week thing; there are several virtual events on Monday and Tuesday (totalling up to roughly 4-5 hours), and then everyone is encouraged to attend (on Wed., Thurs., or Fri.) one or more virtual meetings--with the staff of their congressperson and/or one or both senators. I found it instructive and useful, and also a way to meet interesting folks.