Please note that one moonstone chest will spawn daily anywhere outdoors in the Valley on paved or unpaved ground when you log in to the game. 

A maximum of 3 can be in the Valley at one time before they stop spawning daily. They will remain in the Valley until you clear them.

If you played the game daily for 3 days but did not collect your blue chests, you should be able to see and collect these 3 blue chests.

If you did not enter the game for 3 days, there will be only one chest because blue chests do not spawn in the valley when you are not playing.