Gather all materials 

Place your shirt so it is flat and right side up on a smooth surface. 

Cut along the sides and seams of the shirt so you seperate the front and the back. Do this to all of the shirts.

Take all four fronts and backs of the shirts and lay them out so they are flat.

Draw a box in the middle of each shirt about 3 inches by 3 inches. 

Next take your grass and fill a small bowl with water. Place the grass in the bowl and let the grass sit for about 30 seconds then pour all the water out but use your hand to stop the grass from coming out

Take a pinch of grass and rub it onto the shirt repeat for all of them 

Label each shirt with either toothpaste, washer, vinegar, or shaving cream. Make sure each of your shirts has a title.

Make sure to measure the opacity of the stain before. 

Once all that is done leave your shirts to sit for 24 hours.

Once 24 hours has passed take one of your shirts that says washer and place it in the washer and set the water to warm and do a normal wash cycle, and use a tablespoon of detergent. 

While that is washing, take one of your other shirts that is the vinegar shirt and place it so it is flat. 

Next take your baking soda and place about a teaspoon of it onto the stain. 

Next take your baking soda and place about a teaspoon of it onto the stain next take your vinegar and do the same and then scrub it with a toothbrush for about 1 min (it will help if you dip the tooth brush into vinegar occasionally) 

Then once the vinegar is scrubbed into the stains, take the shirt and place it in the washer when your other shirt is done  and make sure you wash it the exact  same way as the first shirt 

Take the first shirt out of the washer and hang it up to dry

Now you can take another shirt the shaving cream one and take you shaving cream and spray some out onto the shirt, then you can rub the shaving cream into the shirt  and then let it sit for about a 5 min 

When 5mins is up rinse the shirt

Then after that put the shirt  in the washer and make sure you wash it the same as the other two

Find your last  shirt that says toothpaste and squirt a dollop of toothpaste onto the stain

Now you are going to take your lemon and cut in half and take one of the halves and squeeze it into a bowl you should have about ⅛ of a cup

Now take the other half and do the same thing this should bring you to about ¼ cup of lemon juice 

Now dip your toothbrush into lemon juice 

Scrub the stain with a toothbrush for  about 1 min and periodically re dip your toothbrush into lemon juice 

After you have scrubbed the shirt for 1 minute you can take some baking soda and sprinkle a little on top and scrub and let sit for 5 min then rinse

Take the shirt and put it in the washer and make sure to wash it the same as all the other shirts 

Once all the shirts are washed and are dry  you can get out your opacity chart and measure the opacity of the grass stain for each method and determine which one worked the best. Make sure to measure the darkest spot of the stain