Quote Originally Posted by Simon000001 View Post
А как знать надо ли использовать "из" или "от" ?
Я выкопал картофель из моего сада.
Почему не "от" моего сада ?
The basic prepositions for directions are:
"в" (into, motion to inside a location) and "из" (opposite to "в", motion from inside a location);
"на" (onto, motion to the top of a location) and "с" (opposite to "на", motions from the top of a location);
"к" (towards, motion to a location not necessarily entering it) and "от" (opposite to "к", motion from a point near a location to a point far away from it).

There are much more nuances of how to use "в" and "на", of course. I have just provided a simplified mapping.
But anyway, "из" always corresponds to "в" and "с" always corresponds to "на".

У меня в огороде растёт картофель (Potatoes grow in my garden), BTW note, it is "огород" where you grow vegetables, not "сад". "Сад" is usually for fruit trees.
That's why you say: Я выкопал картофель из огорода.

If you say "Я выкопал картофель от огорода", that would sound very strange, as if you started digging potatoes from the edge of your garden and proceeded to somewhere outside of it...

Compare:
Река течёт с горы. - The river flows from the top of the mountain.
Река течёт из горы. - The river flows from inside the mountain (imagine there is some empty cavity inside it). Maybe it flows out of a cave.
Река течёт от горы. - The river flow starts from a point very close to the mountain, not from the mountain itself. Or maybe from the foot of the mountain.

You can think of it this way:
"из" = out of; "с" = from the top of; "от"= starting from.
They are very rough approximations, but they might help to understand the difference.

One more example:
Мы ехали из Самары в Москву 10 часов. = We travelled from Samara to Moscow 10 hours. It means we started the way in Samara and finished it in Moscow. The whole way is assumed.
Мы ехали от Самары до Москвы 10 часов. = We travelled from Samara to Moscow 10 hours. Maybe we started the way much earlier (say, in Yekaterinburg) and continued it after Moscow (maybe to St. Petersburg). But the span between Samara and Moscow took us 10 hours. It is not clear, if the whole way is assumed or a part of it.