As in most MR games, there are important items to have on your farm to help your monsters maintain Stability. In MFDS, these items could only be obtained through Tournaments. It seems to be the same in MFDS2. So, using the basic calendar, here is a list in progress of the items and how/when they can be won. As far as I can tell, each unique items has a stacking effect with each other, but duplicate items do not.

Artemis Statue (Reduced Fatigue) - Class D 9/1
Water Pitcher (Reduced Stress) - Class D 6/1
ShyShy blanket (reduced stress)- Class D 8/3
Ice block (reduced stress)- Class B 9/1
Cricket Bell (reduced stress) -
Old Hearth (Reduced Fatigue)- Class A 2/3
Music Box (Rest is more effective)-

BTW, I want to say here that these items are EXTREMELY helpful once you have them. I think the Old Hearth has to be the best one. I can now go on an expedition and come back only half tired. I can also do 3 hard drills in a row and rest up on a single week.

The wiki I found gives more info on these items and why you need ALL of them. (Wiki confirms that the last 2 items are indeed in the game.)

Item	Effect	Tourney
Artemis Statue	Reduces Fatigue on FIRST week of the each month	Class D 9/1
Water Pitcher	Reduces Stress on FIRST week of every month	Class D 6/1
ShyShy blanket	Reduced Stress during SPRING	Class D 8/3
Ice block	Reduces Stress during SUMMER	Class B 9/1
Cricket Bell	Reduces Stress during FALL	Class C 9/1
Old Hearth	Reduces Stress during WINTER	Class A 2/3
Music Box	Rest is more effective	Class S 10/4

I made this table based on what I know and what the wiki fills in. The wiki provided the names of the tourneys but not the dates. The tourney names helped me find the missing dates (that I apparently missed while looking through the calendar before). But knowing the seasons for each of the Stress items is really helpful and explains why there are so many in the first place.