They were going to grow mold on them as soon as you put them in the ground, so yes, they are still good to use. They might be icky but they are good.

As an animal food moldy Alfalfa is not good, but as a plant food there is no problem. However you need to use care in application so you don't breath that moldy dust.

Thank you both!
I've never used this on the lawn before. Could you say how long it may be before they're *absorbed* ?
Thanks.

How long before they are "absorbed" depends on how active your Soil Food Web is. If you have a good, healthy soil, and the Alfalfa Pellets are small they could be digested in a month. If you do not have that good, healthy soil yet, you have made the transition from "conventional" to organic in the last 3 to 5 years, it might take several months for them to be digested.