There's this game called "Harvest Moon" where you do that. It was on SNES I believe, and N64... not sure if it made it to the Wii...
But Graal is a Legend Of Zelda fangame, not a harvest moon one.
That being said, it would be neat to have some sort of (limited availability of course, through time limit or through value) item that progresses when you 'check up' on it... Something like a plant that grows or gives a small gralat reward once very 24 hours or something...?
Something that has a visual progression that it goes through over time..?