If you live near the beach a box of rocks comes in just about every locker. I have created a rock garden with all of the rocks and sea shells from the last couple of years. I usually don't have a problem selling the shells but here lately I have collected over 20 large abalone shells. They sell but not as quick as some of the others.
I have gotten a couple of boxes like the one you found. I have a local guy that is the president of the local rock hounds. He gives me great info and helps me price them. They sell really well. Right now I have several fossils up for sale. They won't last long. Good luck with yours and if you need info find a rick guy in your area. I have found that they usually love to talk about rocks.