Turf seats are becoming popular again because of a desire to create with the environment, rather than impose upon it. The featured photo came from the Instructible Living website and alongside it, they have a great step by step guide to building a Grass Lawn Chair Couch with photos for each step.
QUICK GUIDE: If you have a sloping bank, you can dig out your seat rather than build it up. Dig out the backrest first to a width of about 1.5 m (5’) and depth of 45 cm (18”) or so and clear away the grass at the top to a width of about 5 cm (2”). Next dig out a flat seat at right angles to the base of your backrest and rake the soil smooth.
Begin placing the new turf, starting with the lip and butting it up to the edge of the grass. If any of it starts to slip down, anchor it by pushing wire through the turf into the earth beneath (a bent wire coat hanger will do the job).
On flat ground, you will have to build upwards instead, using a wooden or metal framework or old bricks can work well. Railway sleepers are easy to obtain and handle, but don’t use second hand ones reclaimed from railways as they will be impregnated with tar and creosote – you should be able to find new ones in a good garden centre. Pack the framework with at least 5 cm (2”) of soil on which to lay the turf.
If you wish to add fragrance, use the same principle but plant with creeping thyme or camomile instead.

Reproduced with permission of North West Parks Friends Forum