The human organism knows what we have to eat? My mother has told that if your organism needs a vitamin, you want fruits include that vitamin. For example you have lack of C-vitamin you would like to eat lemon. Is there any explanation for it, or just it is a myth? The human organism knows that what we have to eat?

Assuming you mean organism, not organisation, it's not entirely false that cravings can be driven by deficiencies. In the case of the eating disorder pica, where a person eats non-food items like dirt and clay, can be caused by iron deficiency (Source). However, that article also suggests the possibility that pica _causes_ iron deficiency by causing the person to eat items that lower iron absorption. So, my answer to your question is, maybe.