There are lots and lots of scalloped summer squash varieties and I've grown many of them and here's a Google link about some of them:
https://www.google.com/?gws_rd=ssl#q...+with+pictures
Two seed vendors that list LOTs of them, the non-hybrid ones, are Sandhill Preservation and Baker Creek, the latter with pictures, the former not, but Glenn Drowns who owns Sandhill was the former curator for Cucurbits for SSE so has a huge inventory and sent many of his varieties to Jere Gettle at Baker Creek shortly after Baker Creek got going.
Jere has travelled to many places overseas and has added to his squash varieties almost every year.
Hope that helps,
Carolyn