Booleans are used to interpret suface overlaps, not to actually join or generate new geometry.
Select both then go to the menu POLYGONS-> COMBINE
then they will be 1 object. Note that you will still have to merge the verticies that touch when you put them together.
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And after calming me down with some orange slices and some fetal spooning,
E.T. revealed to me his singular purpose.
--TOOL, 10,000 Days---
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