The problem with composting perennial plants Dawn, grass being one of them, is that the seeds will normally live in the compost and will germinate again when you come to use it in the garden. However, if you can get enough heat during the compost cycle, and grass cuttings are very good for generating heat, then this should kill off any seeds and it should be ok.

Hello Myron. Thank you, I see. It works a bit like plants seeding down in the garden and coming to life the following year. Hmmm, the compost bins are in full sun but our mower mulches so I dont have grass cuttings, for me then a risky process, thanks I appreciate your reply.

It's not really dependent on your compost bin being in full sun to generate heat Dawn. The biological process which causes the matter to decompose can generate vast amounts of heat. The compost can get so hot that you will be unable to put your hand in it without it burning and if this should occur then the heat that's generated should be sufficient to kill off any seeds. What I meant was that in my experience grass cuttings seemed to be the best thing to cause this nuclear reaction ;o)

Maybe someone else could recommend something that might generate a lot of heat in a compost bin?

Most compost bins aren't usually as big as they need to be to generate and retain the heat. Cooling influence of ambient air temperature is enough to reduce the 'cooking' heat of the compost.
However, anything green, mixed layers, will do to compost (bearing in mind unwanted perennial weeds etc of course), so soft prunings, thin twiggy bits for aeration, grass mowings, but well mixed or they go slimy, and raked up leaves in a few weeks time (autumn!), old veg remains, as M says above. Grass cuttings as a layer, I've found, traps the heat very well, but I later mix it up so it doesn't go slimy.

Thanks again Myron, thanks Worthy.
I understand, much appreciate your comments.