Due to the nature of the preferential binding, the 3/6 has to be 1-1 or greater to do >any< good, and since walnuts have a 0.24 : 1 ratio in favour of omega-6s, unfortunately, you wont getting any benefits of omega-3s from walnuts.
Apart from algae sources, the alternatives are a couple of pints of flax seed every night, or going without so many things that you run risk of malnutrition. So, nuts/seeds aren't a solution.
I am curious what your background is/where you get this info? Because that does not fit with my personal firsthand experience with getting well in spite of an incurable inflammatory condition that is supposed to kill me and frequently makes me suicidal if I eat the wrong things (especially the wrong oils).
Apart from algae sources, the alternatives are a couple of pints of flax seed every night, or going without so many things that you run risk of malnutrition. So, nuts/seeds aren't a solution.