It's happened to me numerous times at my local farmers' market. I'm juggling my wallet, bags of produce and one to two children. I pick out some delectables, submit them for weighing, pay...and leave the bag sitting there. Only later, when I get home, unpack, and find I'm missing valuable items, do I notice.
I've done it so many times I can't even begin to count. Possibly the most disappointing was when I left a bag of two excellent balls of my favorite buffalo mozzarella which was to go into a sandwich that very night.
Somewhere, I imagine, there is a heavenly place for the produce that was left behind, a cozy little kitchen stuffed full of all of the forgotten items that have been left over the years. A place where you could make a really good sandwich.