There is more than one type of crema in Mexico. Broadly speaking, you have “table cream” but they also have sour cream. You will also find slightly different variations on this from El Salvador, Honduras, Guatemala, etc.
Go to the Mexican markets, you can usually find the Mexican versions and probably the stuff from El Salvador.
Crema doesn’t go on everything, however…
If you want to explore beyond your gringo roots, this is the first cookbook I would recommend:
It was part of a series of cookbooks celebrating the major cuisines of the world; it is quite excellent, overall. They are out of print now but you can find them pretty easily. I’d recommend you buy the entire set, but that’s just me. Prices probably start at seven or eight bucks per book.