Open Enrollment It is open enrollment season at Trillium Charter School! Enrollment packets available online at trilliumcharter.weebly.com, and in our school office at 1464 Spear Ave. in Arcata. Openings available for TK-5th grade. Trillium Charter School offers individualized learning on site, and non-classroom based. Contact us at 707-822-4721 or through email at info@trilliumcharter.org.