You are right that what you are seeing is the annual rye. The rye that did not germinate and grow last fall, germinated this spring and is actively growing. Which is exactly what you want.

You are correct that its too early to see native grasses from a first year planting right now. Some of my grasses are just now started to sprout, but those are mature plants.

Yes, I would continue to mow it this year. You can let it grow to about 4" or more, just don't let anything go to seed. I imagine as the summer goes on you will see other weedy plants start to grow too, which is perfectly normal. The key is to not let them reproduce.

And its a pretty small area, so if you see dandilions or garlic mustard or something like that you can remove them by hand to keep them from blooming.

When the plants are small its difficult to tell which is a weed and which is desirable, so mowing is the best choice. Its not going to hurt the natives and will keep the weeds from reproducing.

Thanks so much! I will keep mowing and see how things look next spring.