Add the frozen or fresh peas and corn to a saucepan, along with the thyme, and add about 1 cup of water and set on medium heat to warm the vegetables through. If using canned items, just pour the contents of the cans into a saucepan.
Once the peas and corn are piping hot, drain the liquid, then mix in the butter and garlic salt, mix until the butter is melted, then pour into a serving dish.