If you forget your documents, you might face delays at the U.S. port of entry. CBP may send you to secondary inspection if they are not immediately able to verify your information. You may be able to kindly request a Form I-515A that will allow you to temporarily reenter the U.S.
If you have all of your documents each time you enter the U.S., but you are always sent to secondary inspection, you should file for a DHS redress number far in advance of your next planned travel outside the U.S.
Know Your Rights: What to Do if You are Detained at a Port of Entry (F & J visa holders). This document is provided by the American Immigration Lawyers Association (AILA) New England Chapter, and does not constitute legal advice.