Allergies, maybe to the Grass or anything on the grass do you use pesticides? Does your body tingle any other time or only after grass cutting,
If the tingling and pins and needles sensations are present only after cutting grass,then allergy to grass or the pesticides used can be responsible.
If however,you are having such sensations(called parasthesias) otherwise also,then the cause is other than grass allergy. Chronic paresthesia indicates a problem with the functioning of neurons.Causes may include alcoholism, diabetes, hypothyroidism, hypoparathyroidism, peripheral vascular disease, vitamin B12 deficiency or malnutrition, rheumatoid arthritis,carpal tunnel syndrome,transient ischemic attack, motor neurone disease, or autoimmune disorders like multiple sclerosis or lupus erythematosus. A diagnostic evaluation by a doctor is necessary to rule these out.
Get your blood sugar and thyroid hormones levels evaluated. You can take some vit B12 for some days and see if the tingling is gone or not.Investigations like CT/MRI head ,thyroid hormones,ANA antibodies etc may also be required.
Hope it helps. Take care and pls do keep me posted on how you are doing or if you have any additional queries.