The is a list I've put together of the different names for food as well as good alternatives when what you're looking for just doesn't exist.
Most of the alternative only options you can special order online.
From US to UK
All-Purpose Flour = Plain flour (as opposed to self raising, but it's called "plain flour."
Corn Syrup = Doesn't exist. Alternatives include: Golden syrup and Treacle Syrup.
Baking Soda = Bicarbonate of soda (Not baking powder) This one in particular has caused me a lot of confusion.
Corn Starch = Corn Flour
This one deserves is own section
Jelly = Jam
Jello = Jelly (Jello is not a UK brand and no one will know what it is)
Pudding = Custard
Pudding (UK) = a general term for any dessert.
Shortening = Alternative = Butter, Margarine, or Vegetable Spread
Confectioners Sugar = Icing Sugar
Granulated Sugar = Caster Sugar or any kind of sugar will usually do
Graham Crackers = Best alternative = Plain Digestive Biscuits
Eggplant = Aubergine
Zucchini = Courgette
Coffee Cake. I'm adding this one even though it's not an ingredient because it's caused a great deal of confusion for me this past week. Coffee cake is NOT a breakfast cake used to pair with coffee. It is ONLY coffee flavoured cake.
Plastic wrap = Cling film
Extract (Vanilla Extract) = Essence (Vanilla Essence)
Ham = Gammon
Bacon = Streaky Bacon / (UK) Bacon = Canadian Bacon.
Pickles = Gherkins or Pickled Cucumber. You WILL NOT find normal Dill Pickles, unless you special order them online. End of story. Believe me, I've looked!
Oatmeal = Porridge
Lemonade = Lemonade if (AND ONLY IF) you find it in the juice section. Any other time it is used it means Sprite or some other kind of lemon/lime soda.
Soda = Fizzy Drinks (Silly, I know)
Soda (UK) = Carbonated water
I just ask specifically for what I want. Much easier, as long as you keep in mind restaurants don't carry Dr. Pepper. :( Not even American ones.
Shrimp = Prawn
An entire book could be written on British vs. American food. So I have kept this particular post specific to baking ingredients and some food.