Where on my computer are my LO files sotred so that I can get them and attach them to other documents?
Short answer: where you stored them.
LO has no default location by itself. When the Save dialog is opened, the initial location (directory, folder or whatever name is used) is set per OS default behaviour. You can change it to point to any other you like. Common OSes even offer the possibility to create new directories from the Save dialog.
Now if your question is about where you can find previously saved documents, noone but you can answer this question as @gabix remarked. If you don’t remember, use a search-and-find utility to look for files with pattern .od* (extension family for LO files). If you saved your files in non native format, you’ll need to adapt the search pattern (e.g. .doc* or .xl*) but you’ll likely get false positives in case you also use the other suite.
If this answer helped you, please accept it by clicking the check mark to the left and, karma permitting, upvote it. If this resolves your problem, close the question, that will help other people with the same question.
Tools > Options > LibreOffice > Paths
this will show you were they are saved by default.
you can edit the location
Read the Manual