Chickweed, Stellaria media, a cool weather annual weed. Very easily pulled up but do it before it goes to seed!! Also edible if you care to get rid of it that way :-)

I knew they were nice chairs!! Replacing the seat is easy! Remove the old cane....carefully diggign out the old spline without damaging the wood ( that's the hard part) then You buy the cane already woven... and a length of spline. Soak the cane in glycerin and water to soften and using wooden pegs, push it into the groove where the spline was....when all is tight....squirt some glue into the groove and lay in the spline, firming it up with a rubber mallet. Use an exacto knife to cut the ends of the spline to fit closely. I'll bet ther is a youtube video or two. Once you get the old cane out it's a 20 minute job to replace the cane.

Earthworm. Yes, feel bad about prolonged death; but also for not appreciating the beneficial guys.