LPR mom petition for minor child but they can't provide childhood photos what's next?

You do not necessarily need to submit childhood photographs unless specifically asked. Typically, the birth certificate is sufficient evidence mother-child of relationship. If you do not have a birth certificate or your birth certificate is called into question, you may be asked to produce additional evidence. You may even be required to undergo DNA testing. You can read more about family immigration at http://myattorneyusa.com/family-immigration.