Today & Tomorrow Summaries re-add to Notifications on reboot. Every time I reboot my computer, Today Summary and Tomorrow Summary re-add themselves to my Notification Center. I remove them (click Edit, click the red block button, click Done), and they only stay removed until next reboot. 

I'm the only user on my machine. My account is admin. I sync with iCloud, but I don't use these widgets in iOS either, and they don't re-appear there ever. 

Is there perhaps a pref file I should trash, or a cache I should reset? 

MacBook Pro
macOS 10.12.5 Sierra
It’s possible your Notification Center preference file is corrupted.

Open Finder, then press ⇧ shift ⌘ cmd G. In the popup textbox, type in ~/Library/Preferences.

Locate com.apple.notificationcenterui.plist and delete it. Restart your system and see if the issue persists. If it does, you can pull the file back out of the Trash and restart one more time.