This is some text, and here's some in "double quotes"
"and here's a double quote:" and some more", "text that follows"

"double quotes"
"and here's a double quote:" and some more"
"text that follows"

"(?:\"|.)*?"

>>> preg_match_all('%"(?:\"|.)*?"%', $msg, $matches)
>>> $matches
[
  [ "double quotes",
    "and here's a double quote:",
    ", "
  ]
]