At the two New Year Festivals, your Character will receive a number of items to take home. At the Year End Noodle Festival, he/she will receive about a dozen Buckwheat Flour. At the New Year Day Rice Candy Festival, he/she will receive about a dozen Rice Candy.
The intrinsic value in the case of the Buckwheat Flour is less than that of the Rice Candy simply because there is no other method by which you can obtain Rice Candy. You can buy Buckwheat Flour from Chen for 1080G. The shipping value of Buckwheat Flour, albeit much higher than that of Rice Candy, is not even half of what Chen asks.
As far as shipping values are concerned, the average values of the two items are:
Buckwheat Flour: 450G
Rice Candy: 140G
Cooking any 'raw' item using a single-ingredient Recipe tends to increase the value of the item. These two items are no exception, but the actual profit level with respect to Rice Candy is not that great.
When you roast the same Rice Candy to obtain Roasted Rice Candy, the shipping value is: 175G
Using it to create Bamboo Dumplings will result in the same shipping value.
Remember that these prices represent specific items with specific Rank, Quality, Size and Freshness.
If you use Rice Candy that you stored for a year in a Material Stone Refrigerator, so that it has deteriorated to B Rank, the value may be more like 145G.
If Buckwheat Flour has a shipping value of 450G and you can use it in a single ingredient recipe to create Buckwheat Noodles that ship for 575G, you obviously will make a profit when you cook it, but only if you received the Buckwheat Flour at a Festival or grew it, harvested and processed it yourself.
If you bought it from Chen, you will take a loss by transforming it into Buckwheat Noodles in order to ship it. The only valid reason for doing this would be to ship it once in order to complete your Shipping List, but it would be better to wait until you obtain it at the New Year Festival or prepare it from your own harvest.
The Rice Candy received at the beginning of the 2nd Year is best utilised to obtain new Recipes from the resident Chefs and then to make each Dish in order to ship it. You do need to ship one 'raw' Rice Candy and one Buckwheat Flour in order to complete your shipping list.
Other Festival items that you can obtain are Rice Balls at the Rice Festival and a selection of Pumpkin Dishes from the Pumpkin Festival ceelbration. These actually are worth more in terms of shipping values than either Rice Candy or Buckwheat Flour but are not unique and can be made in your own kitchen.