The only Jingle Bell I got was from fighting in Rome's cave (90ish mobs).
While I was training on chickens in the chicken farm, I ONLY got the Holy & Jolly Bells. Either the Jingle comes from a little higher mobs, or it's just very hard to get.

It doesn't make sense to make you get tons of some, and only very very little of the others since it requires just 1 of each to get the stocking. Do they just want to fill our inventories with unused bells?