sure, a gift for no reason is fine...as well as a new baby gift (they don't seem to think that conflicts with the no birthday rule for some reason) wedding gifts are fine, as well as graduation and anniversary gifts.
The angel...well, when I was a witness I think I would have accepted it, and they may. Some witnesses are a little more strict than others.
Mothers and Fathers day, Valentine day and xmas gifts are all out of course...as well as easter gifts and candy...I personal do not understand why people gift easter gifts....candy sure, but not gifts