The squash (gourd, pumpkin) that existed in Medieval Europe is thought to be the white flowered gourd. This gourd is still cultivated by the Chinese. You can look for the seed or find the gourd in a good Chinese market. Zucchini or summer squash is said to be the closest of modern squashes to resemble the Medieval variety.
Soit pelle l’escorche, car c’est le meilleur. Et toutesvoyes, qui vouldra mectre ce dedans, soint ostez les grains; ja soit ce que l’escorche seule vault mieulx. Puis couvent tranchier l’ escorche pilee par morceaulx, puis pourboulir, puis hacher longuement, puis mectre cuire en gresse de beuf; a la parfin jaunir de saffren, ou jecter dessus du saffren par filectz, l’un ça, l’autre la, ce que les queulx dient frangié de saffran.
Let the rind be peeled, for that is best: and always if you want the insides, let the seeds be removed, though it is said that the rind is worth more, then cut up the rind in pieces, then parboil, then chop lengthways, then put to cook in beef fat: Almost at the end yellow it with saffron or throw saffron thread by thread, one here, another there; this is what cooks call ‘fringed with saffron’. (Hinson, Menagier de Paris, pg. M-20)
Menagier de Paris; Cauldron Bleu Cooks Guild (SCA)