As with most symbols, the meaning of a potato is heavily dependent upon the context in which the metaphor appears. Still growing in the ground, freshly harvested, or on your dinner table, each variance in its appearance can change its possible meanings. Since potatoes grow under ground, they can speak of spiritual sustenance that has not yet been revealed, but remains just under the surface. On the other hand, when it is on your dinner table it can speak of a staple "spiritual" food (a food eaten routinely and in such quantities that constitutes a dominant portion of a person's diet). Just for fun, remember that God loves word plays and puns, so a potato that is germinating can speak of revelation, since that potato has "eyes" to see.
* Symbol meanings provided by www.mydreamstories.com should not be used as a dream dictionary. They are for reference only and both dreamer and interpreter should be careful to listen to the voice of Holy Spirit as to what any particular symbol means in any specific dream.