Please post a picture so we can verify your ID.

If it is groundsel, it's relatively easy to manage because it's an annual. (Well, depending on the amount present.)

One key for groundsel and all other weeds -- NEVER allow them to flower & set seed.

Thanks, Jean. I did have it ID'd by the master gardener and it's groundsel. It's not easy to manage because I would be out there every day pulling the ones that haven't flowered. We have decided to reduce the slope in size. so you are saying that since it's an annual it won't be around next year? It's all in one bed in the backyard too. I've never had this problem before with this obnoxious weed! Thanks!

I think it would still be good to have a picture. We get quite a lot of plants 'verified' by master gardeners which turn out to be something quite different. It will be around next year not because the same plants will flower again but because it will have flowered and set seed which will grow next year. It is extremely hardy and will flower all winter in some climates whenever there is a mild spell. The only way to deal with it it to pull every one you see before it flowers. But as Jean says - it is easy to pull up and it can be got rid of. It just takes regular short sessions - they don't have to be 5 hours long. Little and often is the best way of dealing with weeds like this. And they certainly don't warrant either panic or depression. Look on the bright side - you could have bindweed or knotweed.

You've learned a hard lesson that monocultures are very risky things. One disease or pest can hit the lot. Mixed plantings are much tougher. You've also learned that bare ground won't last long and annual weeds are perfectly evolved to nip in and take advantage of the clear space. Isn't nature wonderful? BTW if it is Groundsel cage birds, rabbits, guinea pigs, etc love it as, I believe, do chickens.