When is disobeying parents a grave sin?

I haven’t found a good answer on here about when disobeying parents is a mortal sin that should be confessed. I try to obey my parents in everything they do, but sometimes they say things and I’m not sure if they’re serious about them so I do it anyways, even if it may be dumb. Here is an example: my father made some food and I took out some of the raw onions and tomatoes since I do not like them, and I could never eat them, so I gave them to my mother who ate them instead as I didn’t want to waste the food, did I commit sin? And another example would be like, just a few minutes ago my grandfather told me to pick up some things outside but it’s currently 9 pm and I didn’t know exactly what I was supposed to pick up, so I asked my mother and she just kind of said no not to worry about it. I know I may sound scrupulous but please ignore that, but when is disobeying them a mortal sin?

Possibly when it’s grave matter. Neither of those situations you describe is grave.
You’re not a slave, you’re a reasonable young person with your own mind and ability to tell right from wrong. Because your dad makes food, you don’t have to eat it if you don’t care to.
Would you be angry at a child of yours in either of those circumstances? Doubtful.
It’s nice that you want to obey your parents but perhaps you could ask them what they want, instead of worrying about sin.
More love, less anxiety.
God bless.

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