Vegetables you can plant in April  (NOTE: May 15th is the last average frost date in Ashland, of course this depends on your elevation)

Beets: Plant in two week intervals through June

Broccoli: Early varieties plant April to mid-May.

Brussels sprout: April through May. In late June start seeds for August transplanting. 

Cabbage: April through May 15th

Bush beans: April 15th through July  

Pole Beans: Wait until May! Plant through June

Carrots: Direct seed until June 15th

Cauliflower: Direct seed until May 31.

Chard: Direct seed until May 30th, then again in August/September for winter harvest

Chives: All month

Collards & Kale: All month, then again mid-July through September for October and winter harvest.

Leeks: Plant through May for winter harvest

Lettuce & Endive: Starts can be planted all month.

Onions: Plant by April 30th

Peas:  Plant enation-resistant varieties up until May 15th

Radishes: Direct seed by April 15th

Rhubarb: All month 

Spinach: Slow bolting varieties ( New Zealand Spinach) April 15 to 30th