Yes, Asparagus will benefit from the nematode repelling scent of tomatoes and also parsley and basil. Early crops like spinach, beets and lettuce can also share an asparagus bed. In my garden I group other perennial veggies like rhubarb and strawberries near asparagus. I do not recommend garlic or onions in between the rows as they can affect the asparagus flavor and some gardeners claim that potatoes do not do well with asparagus nearby.  May you find a companion plant for your asparagus that will make a happy marriage. Keep growing, Marianne Binetti