DEBORAH BLOOM WEARING bike helmets and yellow T-shirts, America's mothers are confronting federal agents in combat gear to protect anti-racism protesters in Portland and, soon, other U.S. cities where President Donald Trump has vowed to crack down. Wall of Moms groups have formed in at least six cities including New York and Chicago in the four days since mainly white suburban moms in Portland started making human walls in front of demonstrators. Carrying signs like "Feds stay clear. Moms are here," and "I'm so disappointed in you - mom," the Oregon women have been shoved and tear-gassed by agents. Some…