Place lima beans in large bowlwith enough water to cover by5 inches. Soak overnight.
Bring 2 cups water anddried mushrooms to boil in smallsaucepan. Using slotted spoon,transfer mushrooms to mediumbowl; reserve liquid in saucepan.
Heat oil in heavy large potover medium heat.
Add onion andgarlic; sauté until onion is tender,10 minutes.
Drain beans; add topot.
Pour in mushroom liquid,leaving sediment behind.
Add 6cups water. Bring to simmer; skimfoam from top. Stir in red pepperand thyme. Simmer partiallycovered until beans are tender, 45minutes. Season with salt. Chopmushrooms; add to pot. Simmeruncovered over medium heat untilbeans and mushrooms are verytender, stirring occasionally andadding water to thin as needed,about 15 minutes longer. DO AHEAD: Can be made 3 days ahead.Cool, then cover and chill. Rewarmbeans before continuing.
Add chard to beans. Coverpot; cook until chard is tender,stirring often, about 8 minutes.Season with salt and pepper.