Bread

Spanish people from Spain   >>> Sounds a little awkward, so I think an English speaker would be more apt to say

"People from Spain... "  OR (more specifically):    " Spanish natives..."

...think there is not a good meal without bread, and I agree. We eat bread for lunch and dinner, but that doesn't mean we eat a sandwich everyday.  We eat bread to accompany the food. For example I can cook meat, seafood or soup, and I will have a piece of bread, too.

When I talk about this with my latin american friends, we realize that they eat rice as we eat bread.  I have been  living for one year in United States, and I am wondering what is the food they use to accompany their meals.

>>> the second part of this sentence is fine, and I wouldn't worry about changing the way you say it, but I think in this case one would be more likely to say

                        "... I am wondering what the food is that they use to accompany their meals."   (this may not even be grammatically correct, strictly speaking.   I'm not sure.  But that's the way the words more often tend to come out).

           OR   " .. I am wondering what food they use to accompany their meals."   (This is definitely grammatically correct)

Again, someone in the USA might say use either of these three ways, so the options above are just informational really.

Also when I arrived in the United States, I realized there are many varieties of bread: white bread, pita bread, pretzel, with garlic, cheese...

Definitely my favorite bread is the french one, because we eat that bread in Spain.

When I go to the/a grocery store in Seattle, it is funny, because I spend a long time smelling the bread. I know exactly how the bread I like smells.

Bread

Very well written!