Help me remember! A children's movie with mice who build a flying machine to reach a magic flower so they...?

can heal the baby mouse? Probably an early 90's or late 80's movie,
possibly Disney but I'm not sure. All I remember is the scene where
they build a flying machine out of sticks and grass and it's raining,
the youngest baby mouse is really sick and the magical "healing"
flower is growing on the side of a hill and they fly up there to get
it. It's like a family of mice on a journey...? Thanks for any ideas!