Happy Pumpkin was a pattern introduced on Fiesta Ware, and by most sources it was discontinued in 2002. The pattern sometimes pops up at this time of year from the vaults, meaning that sometimes you can order a few from Homer Laughlin. You can also find it on the secondary market from private parties. The smiling Happy Pumpkin is on actual Fiesta, not another Homer Laughlin style of dish. It is available directly from the maker at $14.99 for the luncheon plate. They are currently in stock, but in limited quantities. Replacements, Ltd., also carries them.
What you might want to also look for are other pieces. The various serving bowls do not have a pumpkin face on them, but feature a Trick or Treat theme featuring Halloween cats. The other pieces typically have the motif shown below. The exceptions are the round place and the round candlestick holders which have jack-o-lantern faces on them.
These pieces tend to easily get overlooked at clearance and estate sales because if you were not close to them, you would not even imagine that they were Fiesta unless you remembered some of the Christmas plates and how they also had designs on them. Happy Halloween hunting on this pattern. If you find any other good sources as far as physical stores or websites for this one, let me know by comment or email.
I saw the stock on Replacements but haven’t snapped any up yet.
