Are There Any Small Churches Involved With Buddhism?

All churches are small in the sight of Buddha.

Not sure what you mean.  Buddhist temples come in all sizes, even as small as a little house managed by a single monk -- i.e., a one-person monastery--  where people go for teachings, meditation, counseling and religious observances.  That's pretty small.

If you mean by "church" a Christian-oriented group, yes, in a way.  The Unitarian Universalists, for example, are very friendly to many other religions, and may go so far as to introduce some aspects of Buddhism into their services.