The Google Sites Medford Leas Arboretum web page has links to view maps in Google Earth on the web. This page has instructions on how to create those links.
Create Google My Map from applicable spreadsheet
In Google My Map, click on three vertical dots at top of page to right of Map name.
Click on Export to KML/KMZ
Select Export as KML instead of KMZ, then click on Download. (For some reason KMZ fails).
Open Google Earth on web
Click on +New
Click on Import file to project
Click on Upload from device
Double click on downloaded KML file
In the Google Earth on the web display, click on Share at the top right
Click on General Access to make sure that Anyone with the Link can access (not just Medford Leas)
Click on Copy Link
Paste this link on Google Sites web page to share.