The tag for "free-will" currently has the following with my emphasis in bold:
for questions concerning the freedom of choice of rational agents
Are there philosophers who have considered freedom of choice or free will for agents more generally, not only for those agents that are considered "rational"?
Examples of potential agents that are not (perhaps, usually?) considered rational might be pets, house plants or even gastrointestinal tract bacteria. They move and grow. Is there any philosopher that claims they exercise free will in the process of doing so.
I am adding "hartshorne" to the tags since Charles Hartshorne was the source of the answer.