Position two floating action button in Flutter

Use Column and add two floating buttons inside it one is on the top left and the second one is on the bottom right

       Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            Align(
              alignment: Alignment.topLeft,
              child: FloatingActionButton(
                tooltip: 'Increment',
                child: Icon(Icons.add),
              ),
            ),
            Expanded( 
              child: Align(
                alignment: Alignment.bottomRight,
                child: FloatingActionButton(
                  tooltip: 'Increment',
                  child: Icon(Icons.add),
                ),
              ),
            )
          ],
        ),

you can use the stack() widget with positioned() in order to achieve this, for example:

import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Maps and Floating Buttons Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Maps and Floating Buttons Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  GoogleMapController mapController;
  var initialLocation =
      CameraPosition(target: LatLng(-27.56, -58.58), zoom: 12);

  void mapControllerCreated(GoogleMapController controller) {
    mapController = controller;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stack(children: <Widget>[
        GoogleMap(
          zoomControlsEnabled: false,
          zoomGesturesEnabled: true,
          mapToolbarEnabled: true,
          compassEnabled: false,
          myLocationButtonEnabled: true,
          initialCameraPosition: initialLocation,
          onMapCreated: mapControllerCreated,
          onCameraMove: (position) {},
          onCameraIdle: () {},
        ),
        Positioned(
            top: 50,
            right: 20,
            child: FloatingActionButton(
              child: Icon(Icons.textsms_sharp),
              backgroundColor: Colors.blue,
              heroTag: 1,
              onPressed: () {
                //do something on press
              },
            )),
        Positioned(
            top: 50,
            left: 20,
            child: FloatingActionButton(
              child: Icon(Icons.check),
              backgroundColor: Colors.blue,
              heroTag: 1,
              onPressed: () {
                //do something on press
              },
            )),
        Positioned(
          bottom: 50,
          left: 20,
          child: FloatingActionButton(
            child: Icon(Icons.search),
            backgroundColor: Colors.blue,
            heroTag: 1,
            onPressed: () {
              //do something on press
            },
          ),
        )
      ]),
    );
  }
}

here a screenshoot:

Check the below code and screenshot may be this will help you :

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Column(
        children: <Widget>[
          Expanded(
              child: Container(
                width: MediaQuery.of(context).size.width,
                color: Colors.red,
                child: Align(
                  alignment: Alignment.topLeft,
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.start,
                    children: <Widget>[
                      FloatingActionButton(onPressed: (){},child: Icon(Icons.add),),

                    ],
                  ),
                ),
              )
          ),
          Expanded(child: Container(
              width: MediaQuery.of(context).size.width,
              color: Colors.green,
              child: Text('Center',textAlign: TextAlign.center,)
          )),
          Expanded(
              child: Container(
                width: MediaQuery.of(context).size.width,
                color: Colors.red,
                child: Align(
                  alignment: Alignment.bottomRight,
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.end,
                    children: <Widget>[
                      FloatingActionButton(onPressed: (){},child: Icon(Icons.add),),
                    ],
                  ),
                ),
              )
          ),

        ],
      ),
    );
  }