Start of my journey + leg training question

I've just started an intentional schedule for working out regularly. I don't need to lose any weight- in fact I want to gain weight because although I'm generally healthy I don't meet requirements to donate blood. So last week I set out to build some muscle, increase my strength, and hopefully gain some weight in the process.

I know I don't want to start out overdoing it with any form of exercise. I'm working out at home with no fancy equipment. Besides squats and lunges (and variations), and walks in a somewhat hilly neighborhood, what can I do at home to strengthen my legs? Fifty each of squats and lunges goes by so fast and I want to add variety to the workout, not just perform endless reps. Thanks!