Answer: I suspect your grass is hiding some weeds called wild onion. In the spring the leaves look just like grass blades, but as the plants grow - if they're not mowed down with the lawn - they can reach 2' in height. I expect that regular mowing is keeping them low and therefore you can't identify them as weeds. Wild onion is difficult to eradicate with chemicals because the underground bulb stores energy for the plant. You may be able to kill the tops of the plants with herbicides, but the bulb will just send out more leaves. The best course of action is to dig them out of your lawn.
Indian Mock-Strawberry (Duchesnea indica) is a common weed in your gardening region. It looks like a strawberry plant and spreads by underground roots. It makes a nice groundcover but it is invasive and can overtake a garden area quickly. If you want to get rid of it, you can dig it up, roots and all or kill it by spraying with glyphosate (Round-Up). Glyphosate is a vegetation killer and will kill any plant it touches so use it carefully around desired plants. Be sure to read and follow label directions.
Best wishes with your landscape!
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