Phipps Conservatory and Botanical Gardens presents its May Market featuring staff horticulturists, local garden clubs, nurseries, farms and other vendors on the front lawn for a plant sale from 9:30 a.m. to 7 p.m. May 9 and 9:30 a.m. to 5 p.m. May 10. Admission to the May Market is free. The summer flower show opens May 10 with themed railroad displays. Phipps is reopening the Butterfly Forest on Saturday. Conservatory hours are 9:30 a.m. to 5 p.m. daily and until 10 p.m. Fridays. Admission is $15 for adults, $14 for senior citizens and students, and $11 for children ages 2 to 18. Call 412-622-6914 or visit phipps.conservatory.org.

Heinz History Center, 1212 Smallman St., has opened “Pittsburgh’s Lost Steamboat: Treasures of the Arabia.” The exhibition showcases items from the pre-Civil War era, including nearly 2,000 objects perfectly preserved. Center admission is $15 for adults, $13 for senior citizens, and $6 for students and children ages 6 to 17. Call 412-454-6000 or visit www.heinzhistorycenter.org.

ToonSeum, Pittsburgh’s Museum of Cartoon Art at 945 Liberty Ave., hosts an exhibit about the children’s book series “Little Golden Books” through June 30. Hours are 10:30 a.m. to 3:30 p.m. Mondays, Wednesdays and Thursdays, 10:30 a.m. to 7 p.m. Fridays, 10:30 a.m. to 5 p.m. Saturdays and 11 a.m. to 5 p.m. Sundays; closed Tuesdays. Admission is $6 for those over age 13 and $3 for children ages 6 to 12. Senior citizens, college students, veterans and active military pay $5. Call 412-232-0199 or visit toonseum.org.

Children’s Museum, 10 Children’s Way, Allegheny Square, hosts “XOXO: An Exhibit About Love and Forgiveness” through Aug. 31. The museum is open 10 a.m. to 5 p.m. daily. Admission is $13 for adults and $12 for senior citizens and children ages 2 to 18. Call 412-322-5058 or visit www.pittsburghkids.org.

Carnegie Museum of Natural History, 4400 Forbes Ave., Oakland, presents “Race: Are We So Different?, through Oct. 27. Hours are 10 a.m. to 5 p.m. Mondays, and Wednesdays through Saturdays, and noon to 5 p.m. Sundays with extended hours until 8 p.m. Thursdays. Closed Tuesdays. Admission is $17.95 for adults, $14.95 for senior citizens, and $11.95 for students and children ages 3 to 18. Admission after 4 p.m. Thursdays is discounted. Call 412-622-3131 or visit www.carnegiemnh.org.