Yes Bobert and I have emailed that organization and asked them:
It says on your website at http://www.foodfirst.org/progs/humanrts/

"The U.S.D.A. reports that in 2000, nearly 1 in 5 children (10 million) went hungry. (4) "
While reading the referenced USDA report, I can not find that information.
Please direct me to it.
Keep up the good work.

I also sent a request to www.rainbowfund.org
Both of these organizations evidently have good intentions and I am not disparaging them.

Meanwhile at the "leftie" USDA I find:

Household Food Security in the United States, 2003/FANRR-42
  Economic Research Service/USDA
  Table 1—Prevalence of food security, food insecurity, and food insecurity with hunger, by year
                              Food insecure
                                           Without hunger  With hunger
        Total   Food secure    All         among children among children
        1,000  1,000 Percent 1,000 Percent 1,000 Percent  1,000 Percent
  Households with children:
  1998 38,036 31,335  82.4   6,701   17.6  6,370 16.7      331 .9
  1999 37,884 32,290  85.2   5,594   14.8  5,375 14.2      219 .6
  2000 38,113 31,942  83.8   6,171   16.2  5,916 15.5      255 .7
  2001 38,330 32,141  83.9   6,189   16.1  5,978 15.6      211 .6
  2002 38,647 32,267  83.5   6,380   16.5  6,115 15.8      265 .7
  2003 40,286 33,575  83.3   6,711   16.7  6,504 16.1      207 .5
  Children (by food security
  status of household):2
  1998 71,282 57,255  80.3  14,027   19.7 13,311 18.7      716 1.0
  1999 71,418 59,344  83.1  12,074   16.9 11,563 16.2      511  .7
  2000 71,763 58,867  82.0  12,896   18.0 12,334 17.2      562  .8
  2001 72,321 59,620  82.4  12,701   17.6 12,234 16.9      467  .6
  2002 72,542 59,415  81.9  13,127   18.1 12,560 17.3      567  .8
  2003 72,969 59,704  81.8  13,265   18.2 12,845 17.6      420  .6 

Looks like Households with food insecurity and children and hunger maxed out in 1998 at 1% and In 2003 it was down to .6%
Supposing that .6% of households had 20% of the children in the US:

According to the US Census Bureau there were 72,293,812 people in the US under 18 in 2000 so 1 in 5, 20%, would be 14,458,762 million children in 420,000 households = 34 children per household.

Ahhhhhhhh, how does that work Bobert? My math could be wrong and if so I would like to know where.