In Scotland when I was a kid we didn't use pumpkins we used turnips,
We used to go pull the turnips to carve from the local farmers field, he never minded the local village kids helping themselves as we always took them from the outside edge of the field.
this was the same farmer we did potato picking for , our schools in Scotland would close for a holiday so the kids could do the picking, its still a tradition today that the schools close but i doubt many of them pick the spuds.
the turnips always took forever to carve a hollow but were well worth the effort.
we used to suspend them from strings and use them as lanterns when we went door to door trick or treating.
In Scotland we called it " guising " not trick or treat, i'm guessing Guising came from the word Disguising as in the dressing up bit.
bet theres a wiki out there. oh! the memories