If the old brown stains are from being in contact with wood or paper, I don't think there's anything that will work. Wood and paper products contain an acid that gradually discolors fabric as it eats away. Be careful if this is the case, as the fabric will already be weakened in these areas.
What I'd probably try in order are these. (1) Z'out (Target has it in the laundry section, about $3 for a spray bottle). I'd soak it every hour for a day or so, as it can take some time to work on an old stain. It's very safe and has worked wonders on many stains for me -- especially organic stains like blood. (2) Oxy-Clean. Again, soaking for up to 24 hours. (3) color-safe powdered bleach such as Clorox 2. Again, soaking for up to 24 hours. The powders should be dissolved first in hot water, then diluted with cold water.
Someone here posted a picture awhile back of an auction quilt that was very stained and soiled. She soaked it in detergent in her washing machine for several days, changing the soaking water every day. It came out beautifully!