By default, Maven will look for your project's resources under src/main/resources.
Project
|-- pom.xml
`-- src
`-- main
`-- resources
However, all your resources may not be in src/main/resources. Thus, you'd have to specify those directories by adding the following to your POM.
<project>
...
<build>
...
<resources>
<resource>
<directory> [your folder here] </directory>
</resource>
</resources>
...
</build>
...
</project>
So if your resources resides in src/my-resources
Project
|-- pom.xml
`-- src
`-- my-resources
you can specify that directory by doing the following:
...
<resources>
<resource>
<directory>src/my-resources</directory>
</resource>
</resources>
...
Furthermore, you can have several directories by adding multiple <resource> elements:
...
<resources>
<resource>
<directory>resource1</directory>
</resource>
<resource>
<directory>resource2</directory>
</resource>
<resource>
<directory>resource3</directory>
</resource>
</resources>
...