Order some Yaucono coffee and check out some of the entries in the coffee contest.

http://www.puertoricocoffeeshop.com/YauconoCoffee.html

Buy her heirloom beans from Rancho Gordo!

My Puerto Rican babysitter brought me a beautiful wooden mortar and pestle from Puerto Rico, then showed me how to make homemade mofongo with it. Your mil may already have the mortar and pestle and the mofongo making skills, tho. Also think a spice gift from The Spice House would be nice. They have all the aromatics you need in a Latin kitchen, also sell some kitchen implements like the microplane grater. They will package a gift for you.

Do you know if she's a fan of Daisy Martinez? Her cookbook called "Morning, Noon and NIght" came out earlier this year.

I always go to La Tienda.com for Spanish foods. Its exposed me to an appreciation, love, and understanding of Spanish foods. Check it out.

If she's Puerto Rican and really into gourmet Latin cooking, I'm guessing that a lot of the stuff that Rick Bayless has put out would be an appropriate, high-quality gift. He deals primarily with Mexican cuisine, though.

Does she have a platanos peeler? http://www.lococonlosplatanos.com/index.html

Diana Kennedy just released her newest Mexican cookbook about food from Oaxaca. And one of my most cherish cookbooks, received as a gift, is "Frida's Fiestas." You could also buy her a cute apron from Etsy.