One would usually just refer to it as the proximal end of the fruit. In grasses the vestigial remnants of the perianth on the ovary are called lodicules. Otherwise I am not familiar with any other terms in common usage.

As I click submit it occurs to me that I meant distal, not proximal.

Calyx

Some have suggested "calyx". Others have said that were it an apple perhaps, it would be a calyx but the pumpkin being a different sort of fruit it is not a calyx and a better description would be the "vestige of the style" for which no one has found a specific terminology.

I should have thought that pumpkins being such a popular fruit some academic somewhere would have published a fantastic monograph with overwhelmingly tedious details.

The distal end of an apple includes the stamens and style/stigma in addition to the calyx. This is true of most pome fruits.

On woody stems the marks left behind by leaves and buds are called "scars". The same might be used to describe marks left by the perianth or style which are deciduous on a pumpkin.