Spinach is high in folic acid. Cereal is a great way too. I've been deficient in folic acid before and I take my prenatal vitamin and every week and folic acid vitamin to make sure it is not to low.
Bananas are high in folic acid, I believe greens are too and spreads like marmite. Some cereals are fortified with folic acid and there will be some in your pregnancy multivitamin tablets