I am not an expert, but they look like crocuses to me.

Is it an older house, where the previous owner may have had flower bed in various places in the yard?

I agree with knuttle. Crocuses grow from bulbs, so you will have to dig up the bulbs to get rid of the flowers.

Wow you guys are good, that's exactly it. Thanks!

I actually like them in the yard. They give you good shot of Spring and when it's time for your first mow they're ready to be cut down so they cause no extra work for you.

Most definitely Fall Crocus. They'll be gone quick. Dig up the bulbs and plant them under a shady tree. No care needed and they're a great reminder that spring is close this time of year as you just found. They're often used for plant timing in gardens. Don't get rid of them.