This is a short video showing you how I managed to collect both The Gem of the Harvest Goddess and the awesome Teleport Stone during the third year summer season in the Spring mine.
Basically you have to collect 9 Jewels of the Harvest Goddess which can be found only on the following floors in the Spring mine:
B60, B102, B123, B152, B155, B171,B190, B202, B222
you can actually do this in two runs if you are using both save slots and come prepared with 8 Elli Leaves. The trick is to save before each floor once you found the staircase to the level below and have a backup save on your second save slot just in case you don't find a staircase down which can happen sometimes. I recommend you collect 5 Jewels of the Harvest Goddess on your first mine run and the last 4 on your second run.
If you decide to collect the last 4 Jewels like I did in the third year, since you have to go to floor 222 to collect the last Jewel, I also recommend you go down to the very last floor 255 of the spring mine collecting the very helpful Teleport Stone and the recipe hidden in the ground there, you will basically clear out the whole Spring mine doing this and have two of the best gems in the entire game :D Good luck everyone !!