Pumpkin is one of the older, hard-to-find Mosser collie colors. It’s a medium-light opaque yellow mixed with subtle orange. Also available as pumpkin satin (on the right below) and pumpkin carnival.
In 2017, a number of similar looking collies were posted on eBay in large quantities. If you look closely, these have a more “neon” orange and the yellow is almost mustard colored. This is very different from the subtle colors of the original pieces. The sellers have made no claim that they are pumpkin – the muzzle looks a little coarse, like they may have been airbrushed or painted.