No fear, I still have plenty of dandelions left before I'm through, and I expect I will always have more. I am planning to harvest some young greens.
I might get brave and try the nettle or thistle too. I think it's Canadian thistle--it had a purple blossom on it last summer before I chopped down it's seed stalk, and I have dozens of little ones to deal with. I was really astonished at the size of the root system on the big one -- I expected to find a 3 or 4-inch stalk under a big rosette of leaves, but it must have been 8 inches across, and very hard. I only sliced off the top and put a few extra layers of cardboard in that spot, so I expect to see more of this plant as well coming up through my mulch.
I had a lawn in my own house once upon a time, and I was very benevolent towards dandelions -- my neighbors loathed me. However, the community garden is a shared space with rules, and I could lose my site entirely if I didn't comply with them over a long period of time.
The garden site also has lots of comfrey. It actually gets spread around every year instead of being killed by the tilling in the summer-only plots. I'm going to help myself to a few small plants before they till this year, and cultivate it as a
compost plant and herb.