Only seeds I can think of offhand that don't seem to like cold temps are the japanese morning glories, I. nils. Never, ever had a volunteer from them. Oh, and come to think of it, I grow four o'clocks every year from seed and they drop seeds all over the place, but I never get volunteers from them either. If I collect the seeds in the fall, they do fine when I sow them in the spring, but I never get volunteers. Maybe they rot before they get warm enough to sprout?
