There are two authors I would really recommend to you:
Rick Bayless and Diana Kennedy.
Both write about Mexican food and culture with a lot of love and respect and what I have seen thus far is pretty spot on. Rick Bayles had a series (and a book) called something like Mexico, one plate at a time.
One thing you need to know about Mexico (the food and the culture) is that it is highly varied, almost as much as the US. The food from the North is different from that along the coast, etc. It is really hard to ‘tell you about Mexican food’ in a post.
That said, Tex-Mex is based on Northern Mexican food (well, duh!:)).
I’ll go over some of the food mentioned, but keep in mind that my family is from Chihuahua and my answers may be different from someone else’s.
taqueria- most of the ones I have visited (primarily in California) are pretty far removed from true Mexican cooking. They tend to be very americanized, even the ‘mom and pop’ ones.
burritos- contrary to what is sold at taquerias, burritos are generally small and have one filling. They are not the size of a small baby, nor do they have rice, beans, meat, lettuce, etc. There is no one standard filling. Common fillings include: eggs/potato, bean, chile verde, lengua (tongue), chile colorado, etc. I have never seen a burrito in Mexico, however, stuffed with rice.
Chile Relleno- typically made with aneheim chiles in Northern Mexico, but many other areas of mexico use poblano chiles.
Tamales - Christmas food. To me, eating tamales in July is as weird as eating a full course thanksgiving dinner in May. Typically tamales are savory but there are several sweet styles. Tamal is singular. Tamales is plural. ‘One Tamale’ is not gramatically correct. Typically wrapped in corn husks but in other countries banana leaves are used.
Napales - taste kind of like slimey green beans. Taste great with scrambled eggs.
Menudo - tastes great and is a really popular dish, especially on Sunday Mornings. In the north, it served with chopped onions, mexican oregano, lime wedges and bolillos, a white roll.
Tortilla chips - nowhere near as popular in Mexico as they are in the US.
Pico de gallo - to me, it’s chopped. It’s like an assemblage of the ingredients as opposed to a puree.
There are also a lot of salsas. A LOT. Typically, the heat people associate with Mexican food is in the salsas. This way each person can heat up their food accordingly.
Ceviche is a seafood cocktail in which the fish is marainated in lime juice and not cooked.
Raw vegetables and fruit are often served cut up, drizzeled with lime juice and sprinkled with chile powder. Cucumbers, Jicamas, coconuts, oranges, pineapple.
Limes are really popular in general. The limes used are more like key limes, however.
Mexican beer tastes great with lime and a dash of salt.
‘aides’ are very popular and go under the name ‘aguas frescas’. Popular varieties include melon, hibiscus, tamarind, and horchata (a rice drink).
Capirutada (I am sure I am mispelling it) is a bread pudding served at Easter.
There are also a lot of stews and soups.
I could go on and on…