treat
  Type
  General Opinions
Apples  Raw and applesauce
Apple seeds contain cyanide, but not in sufficient quantities to kill.
Asparagus Raw or cooked Okay to feed, but not a favorite.
Bananas  Without the peel  High in potassium, a good treat.
Carrots   Raw and cooked   They like carrot foliage too.
Catfood  Wet and dry
  Feed in strict moderation, perhaps only during moulting 
Cereal  Cheerios, etc.
  
Avoid highly sugared cereal such as Cocopuffs, etc.
Cheese
  Including cottage cheese
  Feed in moderation, fatty but a good source of protein and calcium
Cooked Chicken
  
.
  They may like it and it wont kill them, but it just seems so
.. ummm
 wrong.
Corn
  On cob and canned, raw and cooked
  
.
Crickets (alive)
  Can be bought at bait or pet-supply stores.
  Great treat  provides protein and its fun to watch the chickens catch them.
Cucumbers
  
  
Let mature for yummy seeds and flesh.
Eggs
  Hardcooked and scrambled are a good source of protein, and a favorite treat.
  Feed cooked eggs only because you dont want your chickens to start eating their own raw eggs.
Eggplant
  
.
  
.
Fish / Seafood
  
Raw or cooked
  
Flowers  Make sure they haven't been treated with pesticides, such as florist flowers might be.  Marigolds, nasturtiums, pansies, etc.
Fruit
  Pears, peaches, cherries, apples
  
Grains
  Bulgar, flax, niger, wheatberries,etc.
  
.
Grapes
  
Seedless only.
For chicks, cutting them in half makes it easier for them to swallow.
  Great fun - the cause of many entertaining "chicken keepaway" games.
Grits   Cooked   
"Leftovers"
  Only feed your chickens that which is still considered edible by humans, don't feed anything spoiled, moldy, oily, salty or unidentifiable.  
Lettuce / Kale
  
Any leafy greens, spinach collards, chickweed included.
  
A big treat, depending on how much other greenery they have access to.
Mealworms
(see photo after the chart)
  
Available at pet supply stores.
  A huge(!) favorite treat, probably the most foolproof treat on the books.
Meat scraps
  Not too fatty.
  In moderation, a good source of protein
Melon
  Cantelope, etc.
  Both seeds and flesh are good chicken treats.
Oatmeal
  Raw or cooked
  Cooked is nutritionally better.
Pasta / Macaroni
  Cooked spaghetti, etc.
  A favorite treat, fun to watch them eat it, but not much nutrition.
Peas
  
.
  
.
Peppers (bell)
  
.
  
.
Pomegranates
  
Raw
  
Seeds are a big treat.
Popcorn
  
Popped, no butter, no salt.
   
Potatos
  Cooked only
  Starchy, not much nutrition
Pumpkins / Winter Squash
  Raw or cooked
  Both seeds and flesh are a nutritious treat.
Raisins  .   
Rice
  
Cooked only
  
Pilaf mixes are okay too, plain white rice has little nutrition.
Scratch
  Scratch is cracked corn with grains (such as wheat, oats and rye) mixed in.
  Scratch is a treat for cold weather, not a complete feed. Toss it on the ground and let them scratch for it for something to do. Never feed scratch during hot weather because it raises the chickens body temperature.
Sprouts   What and oat sprouts are great!
   Good for greens in mid-winter.
Summer Squash
  Yellow squash and zucchini
  
Yellow squash not a huge favorite, but okay to feed.
Sunflower Seeds  
Sunflower seeds with the shell still on is fine to feed, as well as with the shell off.
  
A good treat, helps hens lay eggs and grow healthy feathers.
Tomatos
  
Raw and cooked.
  
Turnips
  
Cooked.
  Not a huge favorite
Watermelon
  
Served cold, it can keep chickens cool and hydrated during hot summers.
  Seeds and flesh are both okay to feed.
Yogurt
  Plain or flavored
  A big favorite and good for their digestive systems. Plain is better.