edible non poisenous plants/bushes

you need to get a good herb book  and plant book to help you Identify plants correctly ,i have many books and they are very valuable source of information.Its important with children that you teach them about the uses of plants and what can be poisonous but also as in a school or nursery environment it must be plants that are safe,don't just rely on peoples word.good luck and i am glad you are teaching this.

kerri wrote (see)

.... i work with disabled children ....thank you kerri

Snap!  me too, so I know what you mean. 

Yes, those you've mentioned will be fine, including violas. More, just off the top of my head are:

Sage (different colours)

curly parsley (good colour and texture)

Calendula (pot marigold)

Sweet Rocket

and I've just found this list as I was checking that I was right about Sweet Rocket, so this might help http://www.thompson-morgan.com/edible-flowers 

But I'd avoid Yucca, the leaves are so spikey and often just on a young person's eye level 

If you have a conservatory you could try growing citrus plants from seed - I've grown small plants of lemon, orange and grapefruit - no fruit but little flowers that filled the conservatory with the most delicious scent and yet people with hayfever-type allergies never seemed to have a problem with it.

Best of luck and enjoy 

There are hundreds of herbs, they would all be suitable, with very few exceptions.

Also all the flowers that can be added to salads.

Or red and blackcurrants which aren't as fussy about having acidic soil.