there are seven stardrops in the game.
from the stardew valley wiki:
- Sold for 2,000G at the Stardew Valley Fair.
- Obtained from the treasure chest on floor 100 in The Mines.
- If you marry an NPC, received from your spouse when friendship level reaches 12.5 hearts; if you marry another player in multiplayer, a stardrop appears in a giftbox in front of the player when they enter their home after the wedding. You only get one spouse stardrop, regardless of divorce or remarriage.
- Sold by Krobus for 20,000G in the Sewers.
- Obtained from Old Master Cannoli, in the Secret Woods, after giving him a
- Received in a letter from Willy after attaining the Master Angler Achievement.
- Reward for attaining the achievement A Complete Collection (donating all 95 items to the Museum).