I missed that you had come back with a reply, Coach! It sounds like you have some species of Asclepias! One of the common names is butterfly weed, and people pay money for the stuff you're trying to get rid of! Like dandelions, the seeds "float" in the air, and my guess is that some neighbor pretty close has one/some they're cultivating to attract butterflies! The most common species is A. incarnata--but I really have no way to know if that's the species that's showing up in your yard or not. Some info at the link below if you're interested in more! In terms of getting rid of it, I recommend Weed-B-Gon. You can use that in the grass--it kills only broad leaf plants, and you can use it where there is no grass too. From my experience it works better than Roundup, and it's what I use anywhere I need an herbicide these days--works quite well at getting rid of cottonwood and aspen suckers in the grass! As far as I know all, or at least most, milkweeds have taproots, so the sooner you get rid of them the easier it will be. If you decide to try to pull them, you'll need to get all of the root out or they'll come back from anything you leave behind! If you have a place where you want to grow some to attract butterflies (it's also a host plant for the caterpillars), you can just deadhead the flowers before any seeds form to help keep them from "filling up your yard!" Can't help with "the neighbor" if I'm right that that's where the seeds are coming from! Skybird P.S. The "plant" you were getting into as a kid was most likely dandelions! Here is a link that might be useful: Asclepias incarnata

It might be helpful to take pics before excavating.

Middle row 1,2 3 are Oxalis, Sonchus and Hesperis matronalis. Off to work now so no time to enlarge and study 10 unnumbered photos.

Black Medic, a member of the clover (legume) family that grows best in compacted soils with low levels of organic matter. Short term controls are spraying with plant poisons while long term control is achieved by correcting the soil conditions that it likes to grow in. Start with a soil test for soil pH and major nutrient levels and then dig in with these simple soil tests to see what else needs be done. 1) Soil test for organic material. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top. 2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains’ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up. 3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart. 4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell, to a point. Too much organic matter can be bad as well. 5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.