It depends on the pesticide used. Some will be present, although in tiny quantities, for some time. Others will have dissipated completely. For peace of mind, I would seek your food sources from an unsprayed area.

I use Weed B Gone on my dandelions in my lawn. I find that after a week the weed will become discolored. Then I usually need to treat again (after a week) and 1 week after treatment #2, the weed looks pretty sick, so I'm sure it will die. But, I would not take a chance with using weeds from your lawn. Can you get dandelions from an empty field? Probably no one will have treated those. Public parks also often do not have the funds to treat weeds either, that might also be a good source. Also try school soccer fields, as schools generally do not have funds to treat weeds (you can tell by the sheer overwhelming number of dandelions in the school playgrounds.)

Hi All

I would like to eat the dandelions in my lawn. However, I just moved in and don't know what the previous owners did, as far as spraying herbicides, etc. I found this thread and it kind of answers my question. But, seeing as how almost a year has passed, is it still true that it might be dangerous for me to eat the dandelions in case the previous owners sprayed something last summer? Or are they ok by now?

While it's very unlikely anything was used that could possibly still be present in quantity to present a problem, not knowing what was applied would make me leery of eating from the site. Perhaps you could forage elsewhere for another season; two years wait would provide an interval that should pretty much ease any worries, especially for minor consumption of dandelions.