The carrier has a central vertical support panel structure, and a pair of foldable receptacles extending outwardly from opposite sides of the vertical support structure. The receptacles have automatically-opening bottom walls with symmetrical bottom panels which overlap to even-out the strength of the bottom walls and minimize areas of reduced strength. At least two opposed bottom panels are shaped to interlock with one another to hold the carrier open once it has been unfolded. Elongated, connected reinforcing flanges strengthen the carrier in the vertical direction.