I've actually gone to the stand many times this year without many "must-have's", I've forgotten my backpack several times this year, my coat at least 2 times, my bow once, etc. Obviously I turned back around but dang, I gotta slower down and take my ADD medication!
The regular stuff that's a priority, that if I forget, I ain't too happy.... Primos Roar call, Swaro binocs, rattling horns, SAFETY STRAP!!! (usually have some sort of back-up in the pack), flashlight, etc. It's insane the core items you gotta have and how easy it is to forget em.