It really depends on the type of pickles you are making. I made many different types of pickles over the summer. Dilly beans used dill. Senfgurken use mustard seeds. I made two other variations of those. One using tarragon so they have a cornichon flavor. The other used lemongrass and bay. Bread & butter pickles use pickling spice (which is very simple to make yourself). Pickled beets have cloves, cinnamon & allspice in them. Mustard pickles have a sauce made of powdered mustard and flour - sounds strange, but is fantastic. Pickled jalapenos/serranos have garlic, onion and carrots. Pickled peppers had no spices at all. There are many recipes available on line. I usually refer to my circa 1940's cookbooks for pickle, relish, and preserve recipes. Bottom line, have fun with it! Refer to Ball Blue Book for guidelines on preserving & pickling.

If you are making cucumber pickles look for a combination labeled "Pickling Spice." Recipes might also have dill and/or garlic, and whole hot peppers if they aren't in the blend. You can make cauliflower pickles and others with that blend too.

Dill is a classic! I also like to use various different types of mustard seeds.