These are square columns called biers. The top part is covered by the draped flag. See below for historical reference. Link has examples (go to near bottom of page).
https://www.kayserschapel.com/who-we-are/the-kayser-collection
"Casket biers or stands were used extensively from late 1800's through early 1900's to display casket or coffin on during times of visitation, generally at family's home. Of several sets of antique casket biers in collection the pair of Victorian era oak biers , shown at top, are perhaps the rarest and most beautiful. Most of the sets are covered in black hammer cloth with nickel plated adornments. Examples of hammer cloth covered biers can be seen in other photos. A few of the sets have original oil cloth covers and/or wood shipping containers. "