Planting calendar for March-April for Illinois: What vegetables to plant?

Carrots
Chard
Collards
Kale
Kohlrabi
Lettuce
Onions
Peas
Radishes
Spinach
Turnips
Endive

References:

Burpee Growing Calendar http://buff.ly/1gEZ6Cz
The Garden Planting Calendar for Glenview, Illinois (All Things Plants) http://buff.ly/1gEZ91i
March 2014 Garden Calendar | University of Illinois Extension http://buff.ly/1gEZeC7