I set up a Pick Your Own Vegetable farm this summer in upstate NY. I charged $1.50 per pound for whatever the folks picked. 5 gallon buckets were available for use in the field. When the customer was done picking, I weighed up their harvested items, put them in whatever bag or box I had available.
I took some product to the amish produce auction. 1/2 bushel waxed
cardboard produce boxes were the standard packaging device, but was not mandatory. I packed some items differently-2# green beans in ziplock bags for example.
There are no rules to which a PYO operation must adhere. Courtesy, convenience and customer service objectives would determine the manner of packaging and sale. Nonetheless, if you have not patronized a PYO farm, it is a good idea to bring along a couple of buckets, some bags or boxes, a pocket knife or snips to work with.