I have many of these plants (weeds) in my backyard and they have thorns. How do I take them out of the yard while it is hard to use the lawnmower over them? I researched online to see if it was beneficial and it said it was part of the "thistle" family and it is beneficial to eat but I do not know how, while they did mention a lot of times to be sure to stay covered from the plant while it may cause dermatitis. :-/ I would like to find a way to get these types of weeds out of my yard and in a way to find them beneficial in other ways. Here is a photo of the weed.

Canada thistle (Cirsium arvense) - may also be referred to as creeping thistle. This is a perennial species of thistle and can reach up to 1.5 m in height if you let it. This variety of thistle will flower with globular purple-pink, or less commonly, white heads (see image) and develops an extensive, spreading root system.

You are correct in saying that this plant is edible. You can eat the leaves cooked like spinach or fresh in salads, but you will obviously have to trim the spines off first. The most prized part of the plant is the stem which can be eaten after removing the spines and peeling. You will have to handle the plant while wearing thick gloves though and as it is the spines that are irritants then you will probably be fine once those are removed.

Additional Info:
http://www.wildflowers-and-weeds.com/...

Thistle is a very beneficial plant for pollinators. Bees, flies, beetles, and butterflies all like the nectar of the thistle flowers. We have these all over our yard here in Maine. We try to tolerate them when they pop up in out-of-the-way spots, but they've even taken to growing all around the backdoor....

Thistles are one of those resilient plants that you'll have to come after again and again. It's a war--not a battle. I use a sharp pair of long pruning clippers and a rugged pair of work-gloves. Clip the plant as close to the ground as you can get, then pick it up with your protected hands to dispose of. I would strongly recommend avoiding Round-Up and other such systemic pesticides, which kill indiscriminately, and toxins can drift to other plants.

Here is a great resource to check out: http://www.gardeningknowhow.com/plant...

I just wanted to chime in and say that this may or may not be Canada thistle, so be wary of eating it. Sprouts of Canada thistle (it being a perennial) are generally more up-right and less prostrate on the ground like your image. I think it is possible that instead of being a Cirsium species (i.e. Canada thistle is Cirsium arvense), this is a Carduus species (biennial). Carduus species grow over a two year period generally. The first year looks just like the picture you have, and is called a rosette stage. The second year is the flowering year, where they grow upwards and put out blooms. The anatomy of the leaves relative to the Canada thistle I have seen also makes me think it might be a Carduus species. At this stage it is impossible to tell which Carduus it is (floral anatomy is likely needed for that). I have not read anything about being able to eat Carduus species leaves, so please do check on that before you prepare them as food.

Here are a few images of Canada thistle emerging from the ground:
http://www.oardc.ohio-state.edu/weedg...
You can see they are more upright than your specimen.

An example of a common Carduus species
http://www.nd.gov/ndda/files/resource...
This may not be the species you have, but the anatomy of the rosette is closer.

Both Cirsium and Carduus genera have many invasive species, so you probably want to destroy the seed heads before they go to seed if you decide to keep it around for the pollinators (which do enjoy the flowers).

Try high-concentration acetic acid (very strong vinegar). Research shows it works! http://1.usa.gov/15XkVbD My daughter and son-in-law got rid of a large swath of Canada thistle on their property in Maryland using 20% vinegar in a backpack sprayer.

There are a number of commercially available products that are probably registered as herbicides in your state. Ask at garden centers. It's acceptable for organic growers.

The vinegar dissipates quickly and won't alter soil pH, so you can plant directly into the sprayed areas (though it'd probably be a good idea to put down a layer of black plastic or cardboard and grow squash or melons there this season; give it a whole growing season to prevent last year's seeds from germinating.)

Warning: 15%-20% acetic acid can burn, so spray on a windless day, wear skin and eye protection, and keep the product locked up away from children.

Canada Thistle, Hard to control because of the large root system. Check for herbicides that kill the roots. I believe this type of herbicide is called a systemic herbicide. This plant also grows from the seeds it produces, so you have to worry about getting rid of the roots and the seeds.

It seems to be a thistle, but I am inclined to believe it is a biennial type like musk, bull, Scotch or tall thistle, rather than Canada thistle. Thistles can be difficult to identify without a stalk and flowers. The leaves in the photo seem to be hairy, with fairly uniformly-lobed margins. In contrast, Canada thistle leaves are smooth on the topside (key characteristic), with irregularly-lobed margins. Canada thistle is a creeping perennial, typically found in patches. As a perennial, it is difficult to eradicate because pieces of roots often survive. Biennial thistles have a first year rosette stage (similar to the photo), and produce a flowering stalk in year two. For biennial thistles (if there aren't too many plants), you can eradicate them by chipping out the crown of the rosette with a spade before they bolt and flower.

The only way to successfully remove this WEED from your yard that I have found is to manually dig it up, root and all. I dont believe in spraying chemicals.