For me it's:
Getting into bed and finding assorted items - tonight's was a dummy and a small toy cow.
The cuteness of tiny clothes hanging up all over the house.
How excited and proud they get when they get new shoes! Even my smallest DC who is only 1 loves showing off new shoes.
When they read a new big word and you're like wow how did you know what that said?!
The very rare occasion when they're walking into school and they look back for me and give a little wave 🥹