Here are some suggestions from Scoop:
• Hold the toe of one sock in each hand and swing them together so they twist round each other, and pull them apart quickly, two or three times. It works well with sawdust - should work with any other loose material.
• To clean sawdust and grass clippings from socks use a wire brush - it just flicks off.
• Take a piece of clear packing tape or masking tape - about a 4 inch length works well. Fold it back on itself, making a loop, so that the sticky face is on the outside, then place 2 or 3 fingers into the centre of the ring of tape and work it over the grass clipping covered sock. The stickiness of the tape pulls the grass off. Keep working the tape over the sock, until there is no more sticky left, then make yourself another circle of tape, and keep going until the socks are clear of clippings. This method also works for removing pet hair from your clothing.
Some sources suggest that putting the socks in the dryer before washing dries the grass out so you can get it with a lint roller or hand vacuum.
Work boots can be a pain, but if you’ve got the best socks for work boots, your feet will thank you. Here are the best socks for work boots shared by Socksaddict.com.