Hi Whitehead and welcome to GoY, if you mean Convolvulus arvensis (common name field bindweed) then, yes, it is poisonous.

thanks for your reply

It's one of those plants that's on the cusp. It isn't mentioned by Cooper and Johnson in 'Poisonous Plants in Britain and their effects on Animals and Man' nor is it on the HTA list of potentially harmful plants, though that may be because it is not a plant normally sold by garden centres.

The 'International Poisonous Plants Checklist' has three citations though two use the word 'suspected' in the title and the third refers to poisoning in mice.

Overall, it probably is poisonous but would only be harmful if you ate a great bucketful of it and there's no indication that anyone has ever done that.

It is one of the 'morning glories' and some of the plants given that name do have pretty serious effects so it may be guilt by association.

I believe it has been used in herbal medicine as an emetic. so may not kill you but could make you sick.